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Full text of "Talc deposits of steatite grade, Inyo County, California. Prepared in cooperation with the U.S. Geological Survey"

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STATE OF CALIFORNIA 

EARL WARREN. Governor 

DEPARTMENT OF NATURAL RESOURCES 

WARREN T. HANNUM, Director 

DIVISION OF MINES 

Ferry Building, San Francisco 1 1 
OLAF P. JENKINS. Chief 



AN FRANCISCO 



SPECIAL REPORT 8 



AUGUST 1951 



TALC DEPOSITS OF 
STEATITE GRADE 

INYO COUNTY, CALIFORNIA 



By BEN M. PAGE 
Prepared in Cooperation with the United States Geological Survey 




Digitized by the Internet Archive 

in 2012 with funding from 

University of California, Davis Libraries 



http://archive.org/details/talcdepositsofst08page 



TALC DEPOSITS OF STEATITE GRADE, INYO COUNTY, CALIFORNIA f 



By Ben M. Pace * 



OUTLINE OF REPORT 



Page 
__ 3 



Illustrations — Continued 



\BSTRACT 

INTRODUCTION 5 

Acknowledgments (5 

Location 6 

Topography and accessibility 6 

Climate, water, and timber 

}EOLOGY 7 

Llthology 7 

Geologic structure 9 

Comparative features of individual deposits 9 

Physical characteristics 9 

Origin 12 

Size and shape of ore bodies 13 

Reserves 13 

MIXES AND PROSPECTS 13 

Talc City mine 13 

Alliance mine and Irish lease 20 

Alliance mine 21 

Irish lease 22 

White Mountain talc mine 23 

Florence mine 27 

Trinity talc mine 29 

East End mine and Bob Cat claims 29 

Frisco talc mine 30 

Victory talc mine 30 

Viking talc mine 31 

White Swan talc mine 31 

Lakeview talc mine 31 

Blue Stone talc mine 32 

Willow Creek talc mine 32 

White Eagle talc mine 33 

Eleanor talc claim 35 

BIBLIOGRAPHY 3", 

Illustrations 

Plate 1. Surface geology of the Talc City mine, Inyo 

County In pocket 

2. Geology of B, C, I), and Intermediate levels, 

Talc City mine In pocket 

3. Vertical sections, Talc City mine In pocket 

4. Surface geology of the Alliance talc mine and 

Irish lease, Inyo County In pocket 

5. Geologic plans and section of underground 

workings, Alliance talc mine, Inyo County__ In pocket 

6. Surface geology of the White Mountain talc 

mine, Inyo County In pocket 

7. Geologic cross-sections, White Mountain mine, 

Inyo County In pocket 

8. Geologic map of adits, White Mountain mine In pocket 

9. Geologic map of the South Deposit, Florence 

tale mine, Inyo County In pocket 

10. Surface and underground geology of the 

Frisco talc mine, Inyo County In pocket 

11. Geologic map of the White Eagle mine, Inyo 

County In pocket 

Page 
Figure 1. Photo of ceramic insulators made of steatite^. 4 

2. Photo of ceramic articles made of steatite 5 

3. Index map of steatite deposits 7 

4. Photo of Tale City mine 9 

5. Geologic map of Talc City mine area 10 

6. Photomicrograph of massive dolomite, Talc 

City mine 11 



Figure i. 

8. 

9. 

10. 
11. 

12. 

13. 

14. 

15. 
16. 
17. 

18. 

19. 

20. 
21. 
22. 
23. 

24. 

2"). 



Page 



t Published by permission of the Director, U. S. Geological Sur- 
vey. Manuscript submitted for publication January 1951. 
* Geologist, U. S. Geological Survey. 



Photomicrograph of slightly altered silica 
rock, Frisco mine ]■_> 

Photomicrograph of high-grade steatite from 
Talc City mine i;j 

Geologic maps and section, East Side work- 
ings, Talc City mine 17 

Geology of miscellaneous adits, Talc City mine 19 

Diagram of parts of West and Central ore 
bodies, Talc City mine 20 

Photomicrograph of silica rock from Alliance 
mine o () 

Photomicrograph of silica rock from Alliance 
mine 21 

Photomicrograph of steatite from Alliance 
mine oj 

Cross-section of the Irish lease 23 

Photo of White Mountain mine 24 

Photomicrograph of silica rock. White Moun- 
tain mine 25 

Photomicrograph of silica rock. White Moun- 
tain mine 26 

Map and cross-section of Main adit, South 

Deposit, Florence mine 28 

Cross-section, Viking talc mine 31 

Cross-section, White Swan mine 32 

Cross-section, Willow Creek mine 33 

Geologic section at main quarry, White Eagle 
mine 34 

Photomicrograph of talcose granitic rock, 
White Eagle mine 34 

Sketch section, Eleanor talc mine 35 

ABSTRACT 

Steatite is exceptionally pure talc suitable for the manufacture 
of high-frequency radio insulators and for other exacting uses. It 
was a critical mineral during World War II. At the beginning of 
the war there was a single major domestic source, the Talc City 
mine, Inyo County, California. During the war talc from several 
other mines in California, Nevada, New Mexico, and Montana was 
utilized as steatite. 

California continues to lead in the production of domestic 
steatite. All known steatite deposits in the State are in Inyo County. 
Talc of near-steatite quality occurs in other California counties, 
but has not proved acceptable to manufacturers of high frequency 
insulators. 

At the end of 1942 the known steatite reserves of Inyo County 
were estimated to be only 8(i,7(M) tons and the rate of production was 
computed to be equivalent to about 15,(MK) tons annually. Produc- 
tion slackened somewhat, and exploration and development since 
1942 have revealed substantial tonnages of steatite which tend to 
maintain known reserves. The supply of Inyo County steatite is 
seriously limited, however. 

Many of the Inyo County steatite deposits are geologically 
similar in some respects. Limestone is the most prevalent original 
rock. Massive dolomite of hydrotbermal origin has replaced the lime- 
stone in areas measuring hundreds or thousands of feet in breadth. 
Unaltered remnants of limestone occur as "islands" in the tracts 
of massive dolomite. Silica rock resembling quartzite also forms 
islands in some of the massive dolomite. The talc deposits are com- 
monly ragged, elongated, steeply-dipping bodies in massive dolomite 
or silica rock. They are of hydrotbermal origin and are generally 
localized at lithologic contacts along which some differential move- 
ment has occurred, but some are localized by faults or minor shears 
within a single rock type. There are various host rocks. 

Steatite ore bodies have been formed by the replacement of 
massive dolomite at Talc City. East End. Victory, Trinity, and 
White Swan mines ; steatite ore bodies have resulted from the replace 
meiit of silica rock at Alliance, Irish, Frisco, Viking, and White 



(3 



Special Report 8 




Talc Deposits op Steatite Grade, Inyo County 



fountain mines; steatite has replaced limestone at the Blue Stone 
nd Willow Creek mines; tale of near-steatite quality has replaced 
ranite at the White Eagle mine. Therefore, the steatizing solutions 
re not strictly selective in their action, although they show a prefer- 
nce for certain host rocks. 



INTRODUCTION 

"Steatite" in a mineralogical sense means soapstone 
•r massive talc, but in present-day industry the word has 
. different connotation. In commercial usage and in this 
eport, steatite means exceptionally pure talc l suitable 
i for use as the principal ingredient in certain ceramic 
jodies. Because these bodies are widely employed for 
ligh-frequency insulators in radios and other military 
ind civilian equipment 2 (see fig. 1), steatite was included 
n the list of critical minerals during World War II. 

Although steatite has never been adequately defined, 
t is generally understood to mean certain varieties of 
ale containing less than 1.5 percent CaO, less than 1.5 
percent Feo03, and minute amounts only of other chemi- 
'al and mineral impurities. The commercial designation 
steatite is also dependent upon favorable firing proper- 
ties, and satisfactory electrical and physical character- 
istics of the final product. 3 Commercial acceptance is 
generally contingent, moreover, upon adequate supplies 
i)f uniform material, as the dies of the manufacturer are 
designed for raw material of constant shrinkage prop- 
erties. 

Lava-grade block talc is a variety of steatite dis- 
tinguished by its suitability for machining. It must be 
free of flaws and must not crack during firing. Formerly, 
lava-grade block talc was the only type of steatite used 
for insulators. Now, however, it is employed only in rela- 
tively small quantities for spacers in radar vaccuum tubes 
and for other specialized purposes. Since the discovery in 
the early 1920 's that pulverized talc could be used for 
making insulators, most steatite has been ground before 
firing. It is mixed with a binder, and pressed or extruded 
into the required shapes. Because of these technical ad- 
vances, the definition of steatite does not stipulate blocky 
characteristics. 

During World War II emphasis was placed upon 
the importance of steatite in the manufacture of radio 
insulators, and consumption of the raw material was re- 
stricted to such purposes. However, steatite is equal, or 
superior, to ordinary talcs for many less exacting uses. 
Therefore, it has been used during peacetime in the manu- 
facture of high-quality paper, cosmetics, insulating cores 
for electric stoves, gas burner tips, and many other items. 
The consumption of steatite for certain nonessential pur- 
poses constitutes a problem in conservation. 

Foreign countries, including France, Italy, and 
Manchuria, provided much of the steatite-grade talc used 
in the United States prior to World War I, when Cali- 
fornia became an important producer. During the years 

'A good discussion of talc in general, with references, will be 
found in Engel, A. E. J., Talc and ground soapstone in Industrial 
minerals and rocks : Am. Inst. Min. Met. Eng., pp. 1018-1(141, 1949. 

2 Anon., Talc: Ceramic Industry, vol. 32, pp. 38-40, 1949. This 
gives other references on the ceramic uses of talc. 

3 A Conservation Order of the War Production Board (M-239, 
March 28, 1944, as amended, p. 1) imperfectly defines steatite as 
follows: " 'steatite talc' means naturally occurring magnesium silicate 
both crude and beneficated, suitable for use in the manufacture of 
electrical insulators and containing not to exceed one and one-half 
percent (1J%) lime (CaO), not to exceed one and one-half percent 
<ll%) ferric oxide (FeiOs), and not to exceed four percent (4%) 
alumina (AI2O3)." 



between World War I and World War II, California 
was almost the only domestic source for talc used m 
radio ceramics; when the United States entered World 
War II, ceramic manufacturers depended upon two Cali- 
fornia mines for virtually all their new raw steatite. In 
the first part of 194:5, California steatite was mined at a 
rate equivalent to 15,300 tons per year. California now 
ranks first among the states in steatite production. 




Figure 2. Miscellaneous ceramic articles made principally of steatite. 

Other western states began to produce steatite dur- 
ing and after the war. In 194(i, California yielded 9,600 
tons 4 ; Nevada was in second place with 6,000 tons; Mon- 
tana was third, and New Mexico reported some produc- 
tion. 



* For the same year, the California output of talc of all grades 
was about 75,000 tons. 



Special Report 8 



It must be emphasized that the foregoing data apply 
only to talc of steatite grade. New York, at present, out- 
ranks all other states with regard to non-steatite tale 
production. 

In 1!)41 the Planning Branch of the U. S. Army 
pointed out that steatite insulators were required for all 
military radios, and that the domestic production of raw 
steatite came largely from a single source, the Talc City 
mine in California. At the request of Brigadier General 
Ilines, the U. S. Geological Survey and the U. S. Bureau 
of Mines undertook a talc investigation which was carried 
on during 1942 and intermittently thereafter. 

The U. S. Bureau of Mines made partial analyses 
and beneficiation tests of talc samples at the Southern 
Experiment Station, Tuscaloosa, Alabama, and conducted 
some ceramic and electrical tests at the Electrotechnical 
Laboratory, Norris, Tennessee. 5 The Bureau of Mines 
also made field examinations of some talc deposits, partic- 
ularly in the eastern and southern states. Only a small 
fraction of the information obtained by the Bureau of 
Mines is included in this paper, which is chiefly con- 
cerned with the work of the Geological Survey. 

The Geological Survey mapped or described all 
known domestic steatite deposits and many deposits of 
possible steatite grade, most of which are in the western 
states. The work was largely done during 1942 under 
the direction of G. R. Mansfield, geologist in charge of 
the Section of Areal and Nonmetalliferous Geology. A 
preliminary examination of the known steatite sources in 
Inyo County, California, was made by D. M. Lemmon. 
The subsequent field work was done by L. A. Wright and 
B. M. Page. 

In California 32 talc mines and prospects were 
visited. Those which were known to be producing steatite 
or probable steatite were mapped geologically, both 
underground and on the surface. "Ore" which had been 
approved by steatite consumers was not sampled by the 
Survey, but certain doubtful or low-grade talcs in the 
proved steatite mines were sampled. The IT. S. Bureau of 
Mines tested the samples of substandard talcs to find out 
whether or not beneficiation was possible. The mines and 
prospects in talc deposits of unproved quality were ex- 
amined hurriedly. 

Acknowledgments 

The IT. S. Geological Survey's talc project received 
invaluable aid from any persons and organizations. 
Lauren A. Wright did half the field work leading to this 
report. Several other members of the Survey, including 
G. R. Mansfield and D. M. Lemmon, helped in every 
possible way. The Geological Survey is greatly indebted 
to the Bureau of Mines, particularly to T. A. Klinefelter 
and Richard W. Smith of the Southern Experiment 
Station. Essential information was contributed by num- 
erous mine operators and other interested parties, in- 
cluding Franklin Booth, Otis Booth, Henry Mulryan, 
P. E. Thomas, W. K. Skeoch, W. A. Reid, Jaines McNeil, 
Frank Canal, Roy Coulon, Marlyn and W. E. MacBoyle, 
William Bonham, Joseph Ganim, Watson Rich, Wright 
Huntley, and many others. The thin sections used in this 
study were expertly made by Alexander Tihonravov. 

6 Klinefelter, T. A., Speil, S., and Gottlieb, S., A survey of the 
suitability of domestic talcs for high-frequencv insulators : I'. S. Bur. 
Mines Kept. Inv. 3804, 1945. 






Location 

Inyo County, in east central California, is the out- 
standing steatite province in the nation, in terms of past 
and present production. Most known California steatite 
is in or near the Inyo Range. A particularly important 
part of the area, embracing the notable Talc City mine 
and several other deposits, is the upland between Keeler 
and Darwin, just south of the Inyo Range proper. 

All the proved steatite of California is in Inyo 
County, but elsewhere in the state a few talc deposits are 
possibly of steatite grade. For instance, some of the talc 
in the Ganim mine, Shasta County, has yielded favorable 
analyses, but a large part of the material does not satisfy 
steatite requirements. 6 

Non-steatite talc deposits, such as the tremolitic talc 
deposits of the Silver Lake and Death Valley-Tecopa 
regions of California, are more numerous and much 
larger than the steatite talc deposits, and generally have a 
different geologic setting. These enormous talc resources 
are most prominent in San Bernardino County and in 
eastern Inyo County, 7 and are more widely known than 
the steatite ores farther west. Figure 3 shows the location 
of most of the steatite deposits in California examined by 
the author. The locations of many California talc deposits 
are also given in "Mineral Resources for 1922 ", 8 but no 
distinction is made between steatite and non-steatite. 

Topography and Accessibility 

The Inyo Range is a high north-south fault block of 
the Basin and Range province. It is bordered on the west 
by Owens Valley, and is partly bordered on the east by 
Saline Valley. The latter is an uninhabited desert basin, 
but Owens Valley has several towns, including Olancha, 
Keeler, Lone Pine, Independence, Bigpine, and Bishop. 

The steatite deposits in the Inyo Range and adjacent 
uplands range in altitude from about 2,500 to 7,000 feet 
above sea level. The Talc City mine and nearby talc 
properties are in a hilly terrain readily entered by road ; 
they are less than 3 miles from the paved highway be- 
tween Keeler and Death Valley. Many of the other stea- 
tite localities are not so easily reached, however, being 
more remotely situated in steep canyons on rugged, 
precipitous slopes. These properties are accessible by 
rough, steep, winding roads at best. In the Inyo Range, 
three aerial tramways have been built to deposits of silver, 
salt, and talc, respectively. 

Most of the steatite produced in Inyo County is sent 
by trucks to a narrow-gauge branch of the Southern 
Pacific Railroad. This branch line, which is in Owens 
Valley along the western foot of the Inyo Range ter- 
minates southward at Keeler ; at Owenyo (16 miles north- 
west of Keeler) it is met by the Southern Pacific standard- 
gauge track leading to Mojave and Los Angeles. 

Climate, Water, and Timber 

The Inyo Range is in a desert region which is hot in 
summer and cold in winter. Snow impedes the winter 
operation of the White Mountain mine, but most of the 
other mines are below the zone of heavy snowfall. The 

" (Page, B. M., and Wright, L. A.), Talc in the Ganim mine, 
Shasta County, California ; U. S. Geol. Survey, Strategic Minerals 
Investigation, Prelim. Maps, 1943. 

' Wright, L. A., California talcs : Min. Eng., vol. 187, pp. 122-128, 
1950. 

Diller, J. S., Mineral resources for 1913: U. S. Geol. Survey, 
pp. 153, 155, 157-160, 1914. 

"Sampson, E., Mineral resources for 1922: U. S. Geol. Survey, 
pp. 81-83, 1923. 



Talc Deposits of Steatite Grade, Inyo County 



•egion is generally dry, and water for several of the 
nines is hauled from Owens Valley. There is no timber 
l>xcept at the properties which are over 5,000 feet above 
;ea level. Juniper and pifion, but no large trees, grow in 
iome of the higher areas. 




Figure 3. Index map showing location of California steatite and 

near-steatite deposits on record in 1942. All are in Inyo County. 

Inset gives location of area in outline map of state. 

GEOLOGY 

A reconnaissance of the Inyo Range is described by 
Knopf and Kirk, 9 and the reader is referred to their 
paper for a general discussion of part of the area. How- 
ever, the talc deposits are not mentioned by Knopf and 
Kirk, and the major deposits including those of the Talc 
City mine (see fig. 5) lie to the southeast of the terrain 
covered in the reconnaissance. 

Most of the steatite deposits are associated with three 
kinds of rock : limestone, silica rock, and massive dolo- 
mite. The limestone, Paleozoic ( ?) in age, is the principal 
original rock. The "silica rock" of this report is a 
quartzite-like material ; it may be recrystallized sandstone, 
or it may be a product of hydrothermal alteration. The 
massive dolomite is definitely an alteration product de- 
rived mainly from limestone. 

The typical areal distribution of the three characteris- 
tic rocks is as follows (see fig. 5) : The limestone occurs 

" Knopf, Adolph, A geologic reconnaissance of the Inyo Range 
and the eastern slope of the Sierra Nevada, California ; with a section 
by Kirk, Edwin, The stratigraphv of the Inyo Range: U. S. Geol. 
Survey, Prof. Paper 110, 130 pp., 1918. 



chiefly as extensive tracts, within which arc large areas 
of massive dolomite. The massive dolomite areas contain 
"islands" of unaltered limestone, islands of silica rock, 
and talc deposits. The massive dolomite is the most preva- 
lent rock in the immediate vicinity of the mines. 

The majority of the steatite deposits are lenses or 
irregular masses in dolomite or silica rock. Much of the 
steatite is along contacts between two rock types, but some 
is localized by fractures within a single rock unit. 

Exceptions to the above generalities include deposits 
in which massive dolomite is lacking, or in which silica 
rock is absent. Some steatite is associated with various 
rocks that are not present at the more typical deposits. 

Granitic rocks are exposed within half a mile to 2 
miles of most of the steatite mines, and one deposit of un- 
certain quality is largely within a granitic host rock. 

Lithology 

The rocks of the Inyo County steatite areas are un- 
correlated units which show some resemblances from 
mine to mine. The stratigraphy is not yet understood ; the 
age of the sedimentary formations is not known, some of 
the rocks are secondary products, and other rocks (e.g., 
the silica rock) may or may not have a stratigraphic posi- 
tion. For these reasons, it is impossible at present to give 
a columnar section for the various talc deposits. The 
lithologic features that are possessed in common are de- 
scribed here, and local characteristics and additional rock 
varieties will be treated in the descriptions of individual 
mines. 

Limestone. The oldest rocks in the immediate vicin- 
ity of the steatite mines are limestone. The age is probably 
Paleozoic, but positive evidence is lacking. Undoubtedly 
more than one formation is represented ; however, the 
strata have not been assigned to formational units. 

Expanses of limestone, extending partly around the 
periphery of the principal mine areas, form the back- 
ground of most of the talc deposits (see fig. 5). Limestone 
also occurs as remnants within the mine areas, where 
much of it has been altered to massive dolomite. The sev- 
eral lithologic varieties may be grouped into two main 
types. 

The most prevalent type of limestone, exemplified at 
the Talc City mine, is a well-stratified gray rock with 
subordinate thin white layers a fraction of an inch thick. 
Locally it is slightly fissile, but is not highly jointed. Dur- 
ing weathering it develops smooth outcrop surfaces. This 
rock is easily scratched by steel, and effervesces vigor- 
ously in cold, dilute hydrochloric acid. A few layers con- 
tain poorly-defined crinoid (?) fragments, and others 
contain minute bits of carbonized plant remains. 

A second, less plentiful, type of limestone is dense, 
relatively hard, siliceous, and contains dolomitic beds. 
This variety is black, weathering to a pale-gray or tan- 
gray color, and it commonly contains flint or siliceous 
streaks with coarser texture than flint. It is distinctly 
stratified in beds :] inches to '1 feet thick, but is not thinly 
laminated or platy except where altered. It is scratched 
less easily than pure limestone, and efferveces less readily 
in cold, dilute hydrochloric acid. The "stratified dolomite 
and limestone" of the Talc City mine and the "flinty 
dolomitic limestone" of the White Mountain mine are 
examples of this type of rock. 



Special Report 8 



Silica Rock. A silica rock, consisting of quartz and 
closely resembling quartzite, is prominent in most of the 
Inyo County steatite areas. It forms strong, massive out- 
crops. The silica rock is unstratified, and contains no 
fossils. It is gray where fresh, but in many places it 
weathers dark brown. The brown color is helpful in dis- 
tinguishing the rock from the massive dolomite which 
commonly surrounds it. The silica rock cannot be 
scratched by steel, and when it is struck by a hammer 
sparks sometimes are produced. 

The silica rock generally occurs in isolated, discon- 
tinuous patches of peculiar shapes, within areas of mas- 
sive dolomite (fig. 5). Lack of areal continuity and lack 
of systematic structural arrangement are the most puz- 
zling features of the rock. 

Two hypotheses regarding the silica rock are as fol- 
lows : (1) At one time it may have been sandstone, which 
has since been partly recrystallized. If so, it should prop- 
erly be termed quartzite. Or (2) it may be a product of 
hydrothermal alteration of dolomite. 

The first hypothesis is supported by the fact that 
ordinary quartzites do occur in the Inyo Range; an im- 
portant example is the Eureka quartzite (Ordovician), 
which serves as a marker bed in the range. 10 Some steatite 
deposits of the region are clearly associated with ordinary 
quartzite, as at the Blue Stone mine (fig. 3). Possibly the 
silica rock of most of the steatite deposits is also quartzite. 
This possibility is favored by the texture of some, but not 
all. of the silica rock; locally the quartz grains are well- 
rounded, as in many sandstones. 

The main objections to the theory that the silica rock 
is quartzite are occasioned by the distribution. The rock 
must have been a stratiform sedimentary formation at one 
time, if it is quartzite, but obviously it is no longer strati- 
form in its typical occurrences. The separate patches of 
silica rock cannot be explained as the result of erosion 
of a formerly continuous stratum, because the distribu- 
tion is as erratic at depth as it is on the surface of the 
ground. The field relations cannot be interpreted purely 
as a result of faulting, as the requisite faults for such a 
theory do not exist. If the silica rock actually represents 
former sandstone beds, there are two possible explana- 
tions for its present lack of stratiform continuity: (1) 
parts of the sandstone may have disappeared by con- 
version into dolomite; (2) the sand of the original sand- 
stone beds may have been gathered into separate masses 
by some process which produced the present scattered 
discontinuous bodies of silica rock surrounded by un- 
broken dolomite. According to this view, the gathering-up 
of the sand, forming isolated masses, was accomplished 
before the dolomitization of the bordering rocks, as the 
massive dolomite shows no corresponding deformation. 

The hypothesis of hydrothermal origin readily ex- 
plains the field relations of the silica rock. According to 
this hypothesis, hot waters rose upward through the 
dolomite and altered it to silica rock. This occurred only 
where fractures, temperature, pressure, or chemical con- 
ditions were appropriate; therefore, the silica rock was 
produced not as a continuous mass, but as a number of 
separate bodies. The hydrothermal interpretation is fa- 
vored by the lack of bedding in the silica rock, and by the 
virtual absence of minerals other than quartz; there are 

"' Merriam, Charles W., oral communication. 



practically no grains of feldspar on ferromagnesian min- 
erals. The texture of some of the rock is in accord with 
the hydrothermal hypothesis, as some specimens show 
irregularly shaped grains closely fitted together along 
intricate boundaries. This is inconclusive evidence, how- 
ever. 

Silica rock is second only to massive dolomite as a 
host rock for steatite. Steatite-bearing silica rock gen 
erally occurs as "islands" in massive dolomite. This is the 
relationship at the Alliance mine, for example. However, 
some of the talc at the White Mountain mine is in silica 
rock that is 50 to 100 feet outside the dolomite area. 

Massive Dolomite. Limestone has been altered to 
massive dolomite in the immediate proximity of the talc 
deposits. 

The color of the dolomite ranges from white to gray 
to black, probably because carbonaceous material in vary- 
ing amounts is retained from the original limestone. Out- 
crops of massive dolomite are extensive and prominent, 
and commonly have harsh, hackly surfaces. The rock 
surfaces are criss-crossed by small grooves which look as 
though they had been made by the dull edge of a knife. 
The grooves are spaced approximately ^ to 1 inch apart, 
and are caused by the solution of thin calcite seams that 
occupy joints in the dolomite. 

The massive dolomite is devoid of bedding, unlike the 
limestone of the district, and it contains no remnants of 
fossils. It is tougher and harder than the limestone, but 
may be scratched by steel. The dolomite must be scratched 
or pulverized before it will effervesce in cold, dilute 
hydrochloric acid ; however, the numerous calcite seams 
effervesce more readily and may be misleading. 

The massive dolomite varies in grain size. In many 
specimens the grains are barely discernible with a hand 
lens. In other specimens, they are easily seen by the naked 
eye, and the rock is best described as a dolomitic marble. 

The field relations of the massive dolomite point to 
a hydrothermal derivation from limestone. The dolomite 
areas are partly bordered by unaltered limestone, and the 
limestone beds locally terminate against the dolomite 
rather abruptly. The relationships cannot be explained by 
faulting, as the limestone is not separated from the 
dolomite by gouge, breccia, slickensided surfaces, or other 
evidence of faults. In places the dolomite has invaded 
limestone in tongues and cross-cutting bands, obliterat- 
ing the bedding. Within the dolomite areas, islandlike 
remnants of unaltered limestone are found. The dolo- 
mitized zones are unrelated to topography, open fissures, 
or indications of weathering ; therefore, they cannot be 
ascribed to the action of meteoric waters. 

Massive dolomite is pre-eminent as a host rock for 
steatite. Most of the deposits are in, or adjacent to, mas- 
sive dolomite. This is illustrated by 12 of the 15 steatite 
properties examined in Inyo County. Some of the ore 
bodies are completely enveloped by dolomite, as at the 
Trinity mine, but some are within islandlike patches of 
other rock isolated within the massive dolomite ; the 
steatite-bearing "islands" consist of silica rock, stratified 
dolomite, or limestone. A few deposits are just outside 
the periphery of dolomitized areas. 

Other Rocks. Slate and thin-bedded sandstone, in 
minor amounts, are associated with the limestone of the 
Irish lease (fig. 3), and a small thickness of hornfels 
occurs southwest of the Talc City mine (fig. 5). 



Talc Deposits of Steatite Grade, Inyo County 




Figure 4. View of Talc City mine from the southeast. OH — west 
glory hole ; HF — headframe of main shaft ; BA — B level adit. 

Granitic igneous rocks are exposed in the vicinity of 
some of the talc deposits. Megascopically they appear to 
range from granite to granodiorite or quartz monzonite. 
Some of the granitic areas near the talc mines are located 
as follows : one is between Keeler and Darwin, just south 
of the Talc City mine ; another is on the east side of the 
Inyo Range just north of the White Mountain talc mine ; 
and a very large granitic area, shown by Knopf u be- 
tween Independence and Saline Valley, extends to the 
White Eagle and Willow Creek talc mines near the north 
end of Saline Valley (fig. 3). 

The relations between the plutonic rocks and the 
other petrologic units are only partly understood, but 
Paleozoic ( ?) limestone and hornfels are intruded in some 
places (fig. 5). The granitic rocks of the Inyo Range are 
probably outlying extensions of the plutonic complex of 
the Sierra Nevada. If this is so, their age is probably late 
Jurassic or early Cretaceous. 

Dike rocks ranging from basalt or diabase to light- 
colored felsite occur near the Frisco, Talc City, and White 
Mountain mines. The dikes cut across Paleozoic ( ?) lime- 
stone and the granitic rocks, and small altered dikes have 
been found in the massive dolomite. 

Geologic Structure 

Folds. The unaltered rocks (chiefly limestone) in 
the vicinity of the steatite mines are generally folded. For 
example, north of the Talc City mine there is a pair of 
tightly compressed synclines, south of the mine there are 
several isoclinal folds, and to the east and west of the mine 
the beds dip from 50° to 90° (fig. 5). The rocks of some 
of the steatite areas show no fold axes, but nevertheless 
dip moderately to steeply, and probably represent the 
limbs of former folds. 

Some folds in limestone have been practically obliter- 
ated by dolomitization, the massive dolomite retaining 
only a few remnants of stratified limestone. The orienta- 
tion of the unreplaced strata indicates the probable pre- 
dolomite structure ; this is illustrated at the Talc City 
mine. 

The major folding in the region occurred before the 
emplacement of the granitic intrusions, according to 
Knopf, 12 and is probably late Jurassic in age. It preceded, 
and may have facilitated, the dolomitization. 

11 Knopf, Adolph, A geologic reconnaissance of the Inyo Range 
and the eastern slope of the Sierra Nevada, California: U. S. Geol. 
Survey Prof. Paper 110. pi. II, 1918. 

a Knopf, Adolph, A geological reconnaissance of the Inyo Range 
and the eastern slope of the Sierra Nevada, California: t - . S. Geol. 
Survey Prof. Paper 110, p. 9, 1918. 



Faults. Faults of several ages have been observed 
and inferred. They may be classified as: (1 i pre-dolomit*, 

(2) post-dolomite and pre-steatite, (3) post-steatite. 

Pre-dolomite faults are not positively established, 
but are indicated by incomplete evidence. For example, 
at the Talc City mine early faulting is suggested by the 
apparent repetition of lithologic units that occur as unal- 
tered remnants surrounded by massive dolomite. No fault 
is visible, but perhaps dolomitization obliterated it, leav- 
ing unaltered parts of the hanging-wall block and the 
footwall block isolated in the expanse of dolomite. Any 
faults which existed prior to the hydrot hernial action 
doubtless facilitated dolomitization. 

Post-dolomite and pre-steatite faults are important, 
as they are occupied and bordered by talc in some places. 
They are probably faults of small to moderate displace- 
ment (1 to 100 feet?) for the most part, except at the 
White Mountain mine, where the displacement may have 
been several hundred feet. 

Post-steatite faulting on a minor scale is shown by 
the sheared condition of most of the talc. This sheared 
condition in many places resulted from renewed move- 
ment on pre-steatite faults. An exceptional post-steatite 
fault of great displacement (thousands of feet?) forms 
one boundary of the productive steatite area at the White 
Mountain mine, but most of the other mine areas have not 
been so strongly affected by post-steatite movements. 

Structural Relations of Ore Deposits. 13 Structural 
controls are visible or may be surmised in many steatite 
deposits. Contacts between rock units have favored the 
development of some ore bodies, as at the Talc City mine, 
where much of the steatite occurs along the boundaries 
between massive dolomite and stratified dolomite or lime- 
stone. At the Alliance mine the main ore body is at the 
juncture between massive dolomite and silica rock. The 
contacts between lithologic units were probably incipi- 
ent planes of weakness before the talc was deposited. 
Minor differential movement in the rocks was concentrated 
at the contacts of adjoining lithologic units. 

Faults are likewise effective as structural controls. 
Some of the steatite at the White Mountain mine occurs 
along a fault between dolomitic limestone and silica rock. 
Some minor deposits of the Talc City area are wholly en- 
closed in massive dolomite, which appears to have been 
sheared or faulted on a small scale prior to the deposition 
of the talc. 

In some localities, such as the Victory mine, no struc- 
tural control of the ore bodies is apparent. 

Comparative Features of Individual Deposits 

The following table indicates some of the similarities 
and differences between the various steatite deposits de- 
scribed in this report. One or two near-steatite deposits 
are included. 

Physical Characteristics 
It is generally impossible to distinguish steatite from 
other grades of talc at sight, but most steatite has certain 
common fractures. It is often possible to judge by the 
outward appearance whether or not a material merits 
thorough testing. For final identification, a talc suspected 
of being steatite must be laboratory tested; analyses 

i^The term "ore", which in a strict sense applies to metallic 
deposits, is used loosely in this report to designate talc of steatite 
quality In this paper "ore deposit" or "ore body" means a mlnable 
mass of steatite This usage, although debatable, is well established 
in the steatite mines. 



10 



Special Report 8 




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Talc Deposits op Steatite Grade, Inyo County 



11 



Name of Principal 

deposit country rock 

Talc City Massive dolomite, silica rock, lime- 
stone, stratified dolomite and 
limestone 

East End Massive dolomite, limestone 

Victory Massive dolomite 

Trinity Massive dolomite, silica rock 

White Swan Massive dolomite 

Alliance Massive dolomite, silica rock 

Irish Massive dolomite, silica rock, lime- 
stone, slate 
Frisco Massive dolomite, silica rock, lime- 
stone, felsite dikes 

Viking Massive dolomite, silica rock 

White Mountain Massive dolomite, silica rock, flinty 

dolomitic limestone, felsite dikes 

Florence Massive dolomite, flinty dolomitic 

limestone 

Lakeview Limestone or stratified dolomite, 

quartzite, diabase 

Eleanor Dolomitic marble, silica rock 

Blue Stone Limestone, quartzite 

Willow Creek Limestone, granite 

White Eagle Dolomitic marble, silica rock, 

granite 

for iron and calcium should be made, and preferably the 
aluminum content should also be determined. If the 
analysis shows more than 1.5 percent Fe 2 Os, 1.5 percent 
CaO, or 4 percent Al 2 0a, the talc is probably not steatite, 
although uniform specifications have not been adopted by 
manufacturers. Talc which gives satisfactory analyses 
should be submitted to steatite laboratories or manufac- 
turers for ceramic, electrical, and physical tests before it 
can be classed definitely as steatite. 14 

Steatite shows the principal mineralogical properties 
of talc, 15 of which it is composed. It feels "soapy" to the 
touch, is so soft it may be scratched with the fingernail, 
and is easily cut by a knife. It is not affected by ordinary 
reagents. 

Outcrops of steatite are fairly plentiful at the de- 
posits, because talc is resistant to chemical weathering, 
but the outcrops are commonly eroded flush with the gen- 
eral level of the ground because of the softness of the 
mineral. Wide deposits of steatite may be topographically 
expressed by saddles or depressions. 

In most exposures the talc is more closely fractured 
than the adjacent rocks. At some places it occurs as thick 
leaves or splinters standing on edge. 

Where outcrops are lacking, steatite deposits are 
locally marked by the presence of talc fragments on the 
ground or in the soil ; the pieces of talc, being chemically 
inert, tend to accumulate during the decomposition of the 
enclosing rocks. 

Inyo County steatite is dense, fine-grained, and mas- 
sive except for structures caused by shearing or crushing. 
It is not flaky, fibrous, or schistose with respect to min- 
eral orientation, although in many deposits it is rudely 
platy or slickensided because of shearing. Locally the 
steatite is highly fractured or pulverized. 

" A discussion of requirements and a description of tests by the 
U. S. Bureau of Mines is given by Klinefelter, T. A., Speil, S., and 
Gottlieb, S., A survey of the suitability of domestic talcs for high- 
frequency insulators: U. S. Bur. Mines Kept. Inv. 3804, 1945. 

15 For a complete description of the mineralogy of talc, see Dana, 
E. S., The system of mineralogy of James Dwight Dana, Cth ed., 
pp. 678-680, 1904. 



Rock replaced 

by talc 

Massive dolomite 



Massive dolomite 
Massive dolomite 
Massive dolomite 
Massive dolomite 
Silica rock 
Silica rock 

Silica rock 

Silica rock 
Silica rock, etc. 

Flinty dolomitic limestone, 

massive dolomite 
Limestone or dolomite ; 

quartzite also? 
Dolomitic marble, silica rock 
Limestone 
Limestone 
Granite, etc. 



Structures 
controlling 

ore bodies 
Contacts and shears 



Contact 
None visible 
Minor fractures? 
Minor shears? 
Contacts and shears 
Contacts and shears 

Contacts 

Contacts 
Contacts, faults 

Contacts, faults 

Contacts 

Contacts 
Contact ( s) 
Contact 
Contacts 




Figurk 6. Photomicrograph of massive dolomite, Talc City mine. 
This is the host rock for most of the talc. Uncrossed nicols. 

The common colors of Inyo County steatite are: 
pale gray green, pale green, pale tan green, pale tan, 
pale gray, dark gray, gray black, and white. The first- 
mentioned color is probably most prevalent. Some steatite 
is mottled ; for example, gray and white mottled stea- 
tite occurs at the Alliance mine. Steatite is white or nearly 
white when powdered, regardless of the original color. 
However, raw steatite commonly is not as white as the 
non-steatite talcs of the Death Valley-Tecopa region and 
other localities. 

Much steatite is translucent on thin edges, but this is 
by no means diagnostic When scraped with the blade of 
a' pocket knife steatite yields a powder that is soft and 
smooth to the touch, free of grit, and almost frictionless 
when rubbed between the fingers. 

Some non-steatite talc shares the above characteris- 
tics and cannot be distinguished from steatite except by 
laboratory tests. On the other hand, certain kinds of 



12 



Special Report 8 



Table 1 

Sample* SiOt AhO, TiO t Fe,0, CaO MgO KNaO Ign, Loss Total 

Theoretical 6:1.50 __ __ __ __ 81.7 __ 4.8 100 

1-A 62.80 1.98 0.04 1.30 0.64 28.26 0.47 5.25 100.2 

1-B 58.06 .85 __ 1.21 .48 81.85 1.14 5.68 99.2 

1-C 59.80 1.15 __ 1.25 .08 82.08 .62 5.55 100.03 

1-1) 58.70 .68 __ 1.28 .59 82.50 .22 5.98 99.94 

1-E 60.05 .45 __ 1.86 .0!) 82.10 .18 5.41 99.58 

* The samples came from the following sources: 1-A, probably from Talc City mine; 1-B, Talc City mine; 1-C, White Mountain mine; 1-D, Lenbek mine; 1-E, Talc City mine. 



talc contain megascopic impurities that obviously place 
them in a non-steatite grade. For example, fine needles 
of tremolite or actinolite are commonly seen with the 
'aid of a hand lens; or calcite seams or abundant pyrite 
cubes may be visible. A very bright or very deep green 
color, not merely a pale shade, is also unfavorable, for it 
indicates a high chlorite content. Cubes or thick seams of 
limonite indicate a non-steatite grade, but thin films of 
limonite do not prevent a talc from being classed as 
steatite. 

Inyo County steatite consists mainly of minute talc 
grains, 0.005 to 0.5 millimeter in length. These grains 
are anhedral crystals that are mutually unoriented or 
locally obscurely oriented (figs. 8 and 14). 




Figure 7. Photomicrograph of slightly altered silica rock. Some 

specimens have a sandy texture as above. The large grains are 

quartz; interstitial material is fine quartz and talc. Specimen from 

Frisco mine, near Talc City. Uncrossed nicols. 

Sphene occurs sparingly in microscopic grains in 
some high-grade steatite, and is commonly accompanied 
by leucoxene. Smaller, unidentified mineral specks are 
also present. These minerals do not affect the quality of 
the ore. 

Quartz, representing unaltered relicts of the parent 
silica rock, is found as microscopic grains in some of the 
acceptable steatite of the White Mountain and Alliance 
mines. 

Pyrite, limonite cubes, heavy limonite coatings, and 
calcite grains and veinlets are undesirable impurities in 
some of the ore bodies. Talc containing an appreciable 
amount of these minerals is not of steatite grade and 
must be sorted out if it is mingled with the steatite. 
Calcite from veinlets tends to accumulate in the talc fines 
produced during blasting and handling of the ore, so the 
fines are seldom of steatite grade. 



Partly steatized country rock forms boulders (im- 
pure lumps) in many ore bodies, and occurs around the 
margins of some deposits. The semi-talcose materials must 
be sorted out of the ore. 

Manganese oxide dentrites and very thin, local limo- 
nite films are commonplace, and a pale-pink coating of 
unknown composition is found on steatite in some mines. 
These substances are generally not disadvantageous. 

The compositions of five commercial steatitic talc 
samples from Inyo County, as given by Klinefelter, Speil, 
and Gottlieb, 10 are given in table 1. The analyses are 
compared with the theoretical composition of pure talc, 
H,Mg :i (Si0 3 )4. 

Origin 

The original rock at the site of the steatite deposits 
was predominantly limestone, with a little stratified dolo- 
mite. Shale and sandstone were subordinate ; some of the 
sandstone may now be represented by the silica rock, 
but this has not been proved. 

The original rocks were folded — tightly in some 
areas — and were fractured and faulted. The structural 
deformation assisted the ensuing chemical alteration by 
affording fractures and inclined bedding planes along 
which solutions could move upward. 

Rising hydrothermal solutions penetrated and al- 
tered the fractured formations. The solutions did not 
come from the granitic material now exposed near the 
talc mines, nor from the various dikes, but may have come 
from a deeper source related to the visible igneous rocks. 
The exposed plutonic rocks themselves have been hydro- 
thermally altered in places, as the White Eagle mine, 
and so are clearly older than the alteration. 

The hydrothermal reagents added magnesium to the 
original limestone, changing it into massive dolomite; 
the original stratified dolomite was likewise converted 
into massive dolomite. If the silica rock represents an 
original formation, it too must have been dolomitized 
locally; if it was not an original formation, it subse- 
quently developed as a hydrothermal product in the 
various tracts of massive dolomite. Regardless of the 
origin, the massive dolomite contains islands of silica 
rock, unaltered limestone, and stratified dolomite. The 
hydrothermal changes healed most of the previously 
formed fractures, but a second epoch of fracturing oc- 
curred. The massive dolomite and adjacent rocks were 
sheared in places, and some slippage took place along the 
contacts between lithologic units. 

Hot waters rose through the rocks, moving along the 
fractures and contacts, locally forming talc at a consider- 
able depth below the ground surface. The talc was pro- 
duced by the addition of water and silica to dolomite, 
and by the addition of water and magnesia to the silica 
rock. The steatization of the dolomite involved removal 



i Klinefelter, T. A., Speil, S., and Gottlieb, S. ( op. cit., p. 11. 



Talc Deposits of Steatite Grade, Inyo County 13 

is true at the White Mountain mine. Alliance mine, Talc 
City East Side ore body, and other deposits. In such 
bodies ore boundaries are not distinct. 

Reserves 

!a£fy -" ' . . I* * s no } advisable to publish reserves of the indi- 
vidual steatite properties. In sonic cases the owners are 

unwilling to have the data published, in other cases it is 

.. : . not known whether the tale is actually of steatite grade, 

-\ and as a rule tonnage estimates of steatite deposits are 

!• " ■ -. . grossly in error. The ore bodies are not geometrical, they 

- cannot be projected with assurance beyond the available 

* v •' • ' exposures, the older mine workings are caved and inacces- 
sible, and in many properties development is scarcely 

j •• kept ahead of mining. For these reasons accurate coni- 

j| putations cannot be made. 

^^ V % - The total steatite reserves of Inyo County were esti- 

\2V O.lm m mated by the writer at the end of 1942 as follows ; 

'^V, " Measured 6,000 tons 

i ~, Indicated (additional) 32,100 

Inferred (additional) 48,600 

Figure 8. Photomicrograph of high-grade steatite from Talc City 

mine, showing texture. Large dark crystal near bottom of picture is Tot'il oe -/.<• , 

sphene. Uncrossed nicols. - X, >-' IMI f '">* 

„ , . , , ,. ., , Al . These figures are, of course, inaccurate. Thev are ex- 

of calcium carbonate and carbon dioxide ; and the steati- tremely conservative, and merely denote the order of ma- 

ration ot the silica rock involved the removal of some nitude of the rese rves. If the total of 86,700 tons had bee~n 

silica to make room for the added constituents. Perhaps correct, and if the rate of mining early in 1943 had been 

the hot waters obtained their content of magnesia and maintained, Inyo County steatite would have been ex- 

sihca at various depths from dolomite and silica rock hausted in 1948. Fortunately, although some deposits 

respectively, and redistributed these ingredients. The were worke d out during the war, the discovery of new ore 

vigor of steatizing solutions is illustrated at the White bodies and the f urt her development of old ones tended to 

Eagle mine, where granite and other host rocks have been maintain the reserves in much the same wav that known 

altered to talc. 1 ' Evidently the solutions were not strictly domestic petroleum resources were maintained during the 

selective, although they generally did show a preference past seV eral decades. However, steatite reserves are with- 

for certain rock types such as massive dolomite and silica 0U f doubt seriouslv limited 
rock. 

New or continued hydrothermal activity produced MINES and prospects 
disseminated pyrite in some of the talc bodies, which are 

therefore not of steatite quality. More shearing also took . . c .' ne 

place, and affected steatite and non-steatite talc in nearly v /he ™lc Cl $ mine } s 19 miles by road southeast of 

all the deposits Keeler and 6 miles northwest of Darwin, Inyo County, 

California, in a group of hills near the south end of the 

Size and Shape of Ore Bodies i nvo Range (figs. 3 and 5). Although the area is over 

The individual steatite deposits studied in Inyo 5,000 feet in altitude, it is arid and provides neither tim- 
County by the Geological Survey are very small to mod- ber nor water for mining. There is no city at Talc City, 
erate in size, .containing a few hundred to a few thousand despite the implication of the name. The mine was studied 
tons, and are not nearly as large as many talc deposits of by the writer during a period of about 7 weeks in 1942. 
non-steatite quality. At the White Mountain mine a Literature concerning the Tale City mine is very 
10-year output of about 7,000 tons came from more than meager, although several brief references by Ladoo, 18 
half a dozen separate ore bodies. The largest proved Sampson, 19 Tucker, 20 Waring and Huguenin, 21 and others 
steatite deposits in California are at the Talc City mine, appear in various books and journals. In the existing ar- 
where about 135,000 tons came mainly from two ore tides there is little more than a paragraph or two con- 
bodies not depleted by the end of 1942. cerning the geology. 

In contrast to the above, some of the non-steatite talc History and Production. The mine was first oper- 

of California occurs in deposits that contain from half a ated briefly about 1917 or 1918 under the name of 

million to more than a million tons. Simonds talc mine. In 1918 it was purchased from the 

In general, most of the steatite ore bodies are elon- ^Udoo, R . B .. Talc and soapstone: u. s. Bur. Mines Bull. 213, 

gated lenses Or pods, as much a.S 600 feet in length and pp. 111-117. 1923. Gives geological notes and flow sheet of mill. The 

rn j , • ,1 • 1 t i i -l it L . 1, ■ , mining company is referred to as the Inyo Tali Company. 

50 teet in thickness. In detail they are highly irregular, ^Sampson, E., U. s. Geological Survey, Mineral Resources for 

with rao-opfl outlines fraverl ends offshoots aiul locally 1920, part II, pp. 203-204, 1923. Describes the talc and its technology, 

wnn rag^eu outlines, rrd\eu entis, onsnoois, anu locaiij ^Tucker, w. B., California Div. .Mines Rept. it. pp. 300-301, 

gradational boundaries. Some steatite deposits contain 1920-21. Gives geological notes. Refers to mine as Simonds Talc mine. 

_ -lii e i-i • • 11 1 i 1 Tucker, W. B., California Div. Mines Rept 22, pp. 523-524, 1926, 

many residual lumps of the original host rock, and grade Two paragraphs on geology and development. 

into cou ntry rock full of talc seams and stringers. This u ^^\ ) ^\f^^^^^S{^^S n t^ ttanam D ' V ' * Mi " es RePt 

" Wright, L. A., White Eagle talc deposit: an example of steat- '■" Waring,' C. A., and Huguenin, E., California Div. .Mines Repl 

ization of granite: (abst) Geol. Soc. America Bull., vol. 59, p. 1385, 15, pp 126-127, 1919. Report includes a reconnaissance geologic map 

1948. of Inyo County. 



14 



Special Report 8 



California Talc Company by the Inyo Tale Company, 
which about 1922 became the Sierra Talc Company, the 
present owner of the mine and the largest producer of 
steatite in the nation. This concern has offices at 5509 
Randolph Street, Los Angeles, and mills at Keeler and 
Los Angeles. Messrs. Franklin Booth, P. II. Booth, W. H. 
Booth, and Otis Booth have served as executive officers 
of the company, which is now owned by Mrs. Dorothy P. 
Dodds and Mr. Otis Booth. From 1918 to 1942, Mr. W. A. 
Reid was mine superintendent at Talc City ; since 1942, 
Mr. James McNeil has held this position. 

During the first few years of operation, the mine pro- 
vided raw material for insulating cores of Hotpoint 
stoves. The cores were turned out of block talc, which was 
then fired. It was later found that ground talc could be 
used for the same products, preventing great waste, and 
all the ore is now ground. Much talc from this mine has 
been sold to the paper, rubber, and cosmetic industries. 
However, manufacturers of electrical insulators for radio 
and other equipment began to draw upon the Talc City 
production about 1936, and by 1942 virtually the entire 
output was used in high-grade electrical ceramics. The 
mine is the largest producer of steatite in the United 
States, and prior to World War II it was almost the sole 
domestic source of radio ceramic steatite. 

The Talc City mine is said to have yielded 130,000 
tons by early 1942. In 1941 the year's output was 5,800 
tons, before the advent of the war-time steatite crisis. 
This crisis developed in mid-1942 and strained the ca- 
pacity of the 20-year old mine to the limit. The Talc City 
mine produced approximately 70 percent to 80 percent 
of the nation's wartime steatite supply, an accomplish- 
ment which was only made possible by the adoption of 
more modern mining and engineering methods. 

Mine Workings. The surface of the ground at the 
Talc City mine is characterized by large waste dumps 
(fig. 4), and by several subsidences where enormous gap- 
ing cracks furrow the surface of the ground. 

Underground prospecting and development have 
been carried out exclusively by driving new workings, 
with no geologic mapping (prior to 1942) and with no 
core drilling. Geologic studies are now difficult because 
most of the older drifts and crosscuts are inaccessible. 

Glory holes have been used during the past. The two 
largest are the "West" and the "Central"; in addition, 
there are the "Evening Star" and the "Ridge" glory 
holes (see pi. 1). These were tapped by several adits. 
More recent stoping and drifting at deeper levels beneath 
the glory holes has caused caving, and at present large 
portions of the ground surface and old underground work- 
ings are subsiding. In the upper parts of the caved ground 
a good deal of country rock has become mingled with the 
remnants of talc. 

Since the days when talc was removed from glory 
holes through shallow adits, a maze of deeper drifts and 
cross-cuts has evolved, amounting to several miles of exca- 
vation. Not all of these workings are now accessible, but 
some are shown on the accompanying maps. There are 
two inclined shafts (pi. 1 ). One is on the west side of the 
principal hill, and the other on the east side. The west 
shaft starts at the A level and leads successively to the B 
level (63 feet lower than the collar), the 100-foot level, 
the C level (148 feet below the collar), and the D level 



(about 255 feet lower than the collar of the shaft). The 
shaft continues downward about 50 feet below the D 
level. The D level includes extensive workings, which were 
largely obstructed by caved talc and country rock at the 
time of the writer's field work (1942). According to Mr. 
Henry Mulryan, the D level was reopened and was yield- 
ing a substantial tonnage of steatite in 1946. Various inter- 
mediate levels (pi. 2) are not reached from the main 
shaft directly, but are connected by winzes or raises with 
the levels enumerated. In addition to the shaft, the nearby 
B level adit allows access to the workings (pis. 1 and 2). 

The eastside shaft was abandoned for some time and 
was reopened in 1942. Drifts branch from it at depths of 
58 feet and 94 feet below the collar. The east side work- 
ings are now connected with the main workings, but were 
separate in 1942. 

In addition to the principal shafts and workings, 
about a dozen miscellaneous adits and shafts are con- 
nected imperfectly or not at all with the rest of the mine. 

Operation. The operational history of the mine may 
be divided into tw T o unequal parts, the first of which pre- 
vailed until the middle of 1942. The second part had just 
begun at the end of the writer's field work. 

Before 1942, glory holes and underground caving 
involved great waste and danger. Occasionally ore was 
removed by simply taking out a section of lagging in a 
drift, allowing the adjacent broken talc to slide out onto 
the floor. More generally, the ore bodies were partly sur- 
rounded by workings driven in substantial country rock 
that was less likely to collapse; slanting chutes (raises) 
were then constructed into the nearby talc. The ore 
usually "mined itself" after the stopes reached an 
appreciable size, particularly after the ground had been 
disturbed by mining at deeper levels. During a period of 
months material was drawn from the chutes until broken 
country rock predominated over the talc fragments, or 
until dolomite "boulders" repeatedly clogged the chutes, 
halting the mining at that particular place. Premature 
stoping of ore near the D and C levels caused settling and 
shattering of overlying ore, and the partial collapse of 
drifts and stopes, many of which were not yet worked out. 
Afterwards, the talc remaining above the D and C levels 
was approached with difficulty. 

Since the middle of 1942, during the later operations, 
an effort has been nade to avoid caving. In the east side 
workings, square sets have been used, and the ore has been 
systematically removed. 

The talc is trammed by hand from the stopes to 
buckets in the shafts. At the surface the ore is carefully 
hand-sorted, to eliminate visible calcite, dolomite, iron 
oxide, and excessively dark talc. The bulk of the lump talc 
is of steatite grade ; the screenings, however, are higher 
in lime and are not used for steatite. The steatite is sent 
by truck 19 miles to the company 's mill at Keeler, on a 
spur of the Southern Pacific Railroad. There the talc is 
ground in a Raymond mill with a whizzer air separator on 
top, then it passes through a cyclone. Tests for lime con- 
tent, color, and fineness are made frequently during each 
mill run. The product, which is minus 200-mesh, is sacked 
for shipment, representative samples being retained for 
reference. All shipments of Talc City steatite are now 
ground talc, which is nearly pure white regardless of the 
color of the ore. Most of the product is sent by rail to 
manufacturers in the eastern states. 



Talc Deposits op Steatite Grade, Tnyo County 



15 



General Geology. The general geologic setting of 
the Talc City mine is shown on the sketch map (fig. 5), 
and the areal geology at the mine is shown in greater 
detail in plate 1. 

The talc occurs as irregular, elongated bodies in an 
area of massive dolomite. The dolomite is almost sur- 
rounded by Paleozoic (?) limestone from which it was 
derived by hydrothermal alteration. Within the area of 
massive dolomite there are remnants of unaltered lime- 
stone, remnants of sedimentary stratified dolomite, and 
peculiar "islands" of a silica rock that resembles quart- 
zite. A large mass of granitic rock that has intruded the 
limestone extends to within 3,000 feet of the mine. 

Limestone (Paleozoic?) a'most encircles the mine at 
a distance, and small patches of it are present near the 
workings (fig. 5 and pi. 1). Most of this limestone is gray, 
with a few thin white layers. 

A stratified dolomite and limestone, different from 
that described above, occurs near the talc deposits (pi. 1). 
Its stratigraphic relationships are unknown, as it is prin- 
cipally found as isolated patches surrounded by massive 
dolomite. There is a marked difference between the charac- 
ter of the rock underground and the character on the sur- 
face. Surface exposures are distinguished by a tan to gray, 
smooth "buckskin" appearance, and by streaks and blebs 
of rusty, siliceous material that jut out in relief. Micro- 
scopic examination of the stratified dolomite and lime- 
stone collected from outcrops shows a sprinkling of coarse 
silt and fine sand, largely quartz, in a fine-grained car- 
bonate matrix. Underground, the rock resembles shaly 
limestone and effervesces freely in cold, dilute acid. It is 
much softer, more fissile, and much less dolomitic than 
where exposed in surface outcrops. Probably these differ- 
ences are caused by hydrothermal alteration near the ore 
bodies ; most of the underground exposures of the strati- 
fied dolomite and limestone are in the immediate vicinity 
of the talc. Many of the workings within this type of rock 
have ragged, splintery, somewhat unstable backs and 
walls. 

A silica rock closely resembling quartzite forms 
prominent outcrops at the Talc City mine. It characteris- 
tically occurs as isolated, discontinuous patches of peculiar 
shapes within massive dolomite (pi. 1), and its strati- 
graphic relationships are unknown. 

Massive dolomite, utterly different from the strati- 
fied dolomite and limestone, is the predominant rock at 
the Talc City mine, and envelops or borders the talc 
deposits. It is a product of hydrothermal alteration, and 
was chiefly derived from limestone ; it forms a tract 2,000 
to 3,000 feet wide, and interrupts the expanse of gray 
limestone that constitutes the neighboring terrain (fig. 5). 
Within the area of massive dolomite are a few patches of 
unaltered gray limestone, tan stratified dolomite and 
limestone, and silica rock. The massive dolomite is devoid 
of stratification, has harsh, hackly outcrop surfaces, and 
ranges in color from pale gray to gray black. The single 
specimen tested by the writer was iron-free. The rock 
consists of subhedral to anhedral dolomite grains which, 
in most samples are 0.015 to 0.05 millimeter in diameter 
(fig. 6). The texture is coarser in the northeastern parts 
of the B level and C level of the mine, and these coarser 
facies are best described as dolomitic marble. 

Diabase occurs in three or four very small dikes 
within the mine area. The dikes are from 2 inches to 2 



feet thick, and are quite irregular, having filled branch- 
ing joints in the massive dolomite. The word "diabase" 
is loosely applied here, as the original texture and min- 
erals can only be surmised. Most of the rock is altered to 
a soft, fine-grained, dark-green material that disinte- 
grates like shale in the open air. The best-exposed dike 
may be seen at the mouth of the A-level adit; near the 
main hoist house. This dike shows a relict flow structure 
and amygdules of quartz and calcite. The chief mineral 
is matted, fine chlorite, with talc and some kaolinite ( ?). 
There is a sprinkling of microscopic pyrite and limonite 
specks, and a few minute grains of sphene. 

Outcrops of granitic rock (granodiorite?) are within 
3,000 feet of the Talc City mine (fig. 5). This rock is 
exposed over a large area ; it is cut by many basalt dikes. 
The granitic rock is bordered by hornfels in places, but 
elsewhere it has intruded limestone of the type that is 
found at the Talc City mine. 

Geologic Structure. Folds, and perhaps a major 
fault, existed at the site of the Talc City deposits before 
the hydrothermal alteration of the rocks took place, but 
these structures have largely been effaced by dolomitiza- 
tion. The limestone that partly encircles the mine is 
strongly folded ; the steeply dipping strata strike toward 
the mine, but are obliterated at the edge of the dolomitized 
area. Within the area of massive dolomite, the isolated 
patches of gray limestone and tan stratified dolomite are 
unaltered remnants of formerly continuous formations. 
The strata composing these remnants follow two trends 
(pi. 1). In the southern part of the mine area the strike 
of the remnants varies only a few degrees from north, 
but in the northern part the strike is west-northwest. The 
elongated talc bodies reflect imperfectly the strike of the 
neighboring stratified remnants, hence the talc also shows 
two dominant trends. These two trends were probably 
inherited from the strike of beds on two limbs of a fold, 
or on two sides of a fault. 

The existence of a pre-dolomitization fault is also 
suggested by the repetition of lithologic units at the West 
ore body and the Central ore body (pi. 1). The arrange- 
ment and lithology of silica rock and stratified dolomite 
and limestone is almost identical in these two parallel 
ore bodies. Perhaps faulting of an inclined series of strata 
brought two formations into position side by side ; dolo- 
mitization then obliterated the fault and engulfed all but 
the present remnants of the original formations. 

Post-dolomitization faults of small to moderate dis- 
placement are present. Faulting has produced conspicu- 
ous effects within and along most of the larger talc bodies. 
Much of the talc was formed by replacement of wall rock 
along faults and subsequent mechanical movements have 
largely been concentrated in the ore bodies which are 
physically very weak, rather than in the strong country 
rock. Consequently countless, interlacing slickensided 
surfaces within some of the talc masses give the illusion 
that slippage has amounted to thousands of feet. 

The movements that produced such pronounced 
effects in the talc yielded a few small, inconspicuous 
shears only in the massive dolomite. Most of the shears in 
dolomite are marked by an inch or two of gouge and 
breccia; some are bordered by silicified and sparsely pyri- 
tized zones. Some show solution effects of ground water, 
which has utilized them as channels, making some of the 
fissures as wide as 3 feet. 



16 



Special Report 8 



Some shears in the dolomite are not parallel with 
the ore bodies. Most of these are of little importance and 
are not traceable for more than 100 feet, but a possible 
exception is a fault ( ?) called the "Watercourse" which 
is said to terminate the Central ore body. The under- 
ground workings at the ' ' Watercourse ' ' were inaccessible 
at the time of the mapping. 

Breccia zones poorly defined in comparison with the 
distinct shears, were noticed in the massive dolomite in a 
few places near the mine. They are mostly recemented 
with calcite. Some of them are linear, and others have no 
geometrical form, but none of them show fault surfaces. 
Large-scale phenomena of a different sort occur a quarter 
of a mile south of the mine, and also half a mile east of it. 
Here breccia in zones over 150 feet wide resembles a 
coarse mosaic, in which well-separated fragments of gray 
dolomite are bound together by white calcite. There are 
no distinct borders or fault surfaces along the zones. 

The Talc. The Talc City ore is fine-grained, with 
no megascopic flakes, needles, or fibers. Some of it is 
highly sheared and slickensided, but some is less dis- 
turbed and is moderately massive when first opened up 
in the mine ; upon exposure,- incipient cracks open up and 
often produce a crude, irregular platy structure. The talc 
is softer than the fingernail but is quite brittle. Thin 
edges are translucent. Pale gray green, with or without 
a tinge of tan, is the typical color of the best steatite but 
some of the talc is dark gray and some is dark brown. 
The darkest varieties are said to contain more iron and 
alumina than the light-colored material, and most of them 
are not steatite. 

Megascopic impurities in some of the talc include 
limonite cubes that range from pin-point size to one- 
eighth inch, veinlets and coarse chunks of calcite, and 
inclusions of dolomite or partly altered limestone country 
rock. Talc containing these substances is sorted out. More 
commonplace but less serious are thin stains of iron oxide, 
which do not contribute appreciable amounts of iron 
unless very abundant. Some thin dendritic films of man- 
ganese dioxide are also found, but these are not harmful. 

The run-of-mine ore is of steatite quality, and some 
of the select material is exceptionally pure. The follow- 
ing analyses, kindly furnished by the Sierra Talc Co., 
are representative of the quality being shipped as steatite : 

Loss 
SiO, MgO AW, CaO Fe,Oj Alkalis on ign. 
Sierramie #1 __ 50.61 30.01 1.65 0.84 0.92 0.26 5.04 
Sierra 
Hi-Grade #1 __ 60.56 30.19 1.46 0.80 0.00 0.22 5.68 

The accompanying photomicrograph (fig. 8) shows 
one mineral impurity only, a minute crystal of sphene. 
Other specimens of the talc show sparse microscopic 
specks of sphene, leucoxene, and an unknown mineral 
that occurs in extremely small equant grains of low relief. 

The steatite is essentially an aggregate of microscopic 
matted talc flakes, shreds, and stubby slivers, the last 
mainly showing a length-to-width ratio of 2 :1 or 3 :1. 
Most of the grains are only 0.005 to 0.025 millimeter long, 
and most are anhedral to subhedral. There is no obvious 
preferred orientation of the bulk of the tiniest flakes, but 
the larger grains exhibit one or two directions of imper- 
fect parallelism. Some of the largest flakes and shreds 
(about 0.5 millimeter long) occur at random, but others 
form continuous, ill-defined, crooked streaks with the 



talc crystals oblique to the borders of the streaks. A few 
of the larger shreds are in splotches with a subradiating 
arrangement. The writer has not seen any relict textures 
inherited from earlier minerals. Many non-steatite talcs 
show remnants of tremolite, but the Talc City ore does not. 

Occurrence. The geologic relationships of the talc 
are illustrated in the accompanying maps and sections, 
figures 9 and 10, plates 1-3. Without exception the talc 
is associated with the massive dolomite. Some talc is in or 
next to the residual islands of sedimentary rock sur- 
rounded by dolomite, but some is in the massive dolomite 
itself. Most or all the talc of steatite grade has been derived 
from massive dolomite. 

More specific ore controls include the following : (1) 
Contacts between massive dolomite and stratified dolomite 
or limestone, (2) shears, and to some extent joints, within 
the massive dolomite, and (3) contacts involving the silica 
rock. Significant quantities of talc are found in places 
where only one of these three features is present, but all 
three ore controls are evident along parts of the large 
Central ore body. 

The talc deposits are elongated, narrow, ragged, and 
irregular in plan and cross section. In a general way they 
dip steeply toward the southwest. Some have definite 
hanging walls or footwalls with polished and grooved 
surfaces, and with thick talc gouge. "False walls" are 
commonplace where the ore has been sheared and slicken- 
sided internally. Some talc masses have no distinct hang- 
ing wall or footwall; some have not even a moderately 
regular boundary, and in some masses, the contact with 
the country rock is gradational. Most of the ore bodies 
contain at least a few "boulders" (rounded inclusions) 
of dolomite. 

Some large offshoots containing hundreds of tons of 
talc extend from the main bodies at unpredictable inter- 
vals. In contrast to the large offshoots, thin stringers of 
talc branch from the main talc masses, following joints; 
they rarely widen out into another ore body. On the other 
hand, stringers of talc within well-defined shears in a 
few places do lead to ore bodies. Even locally barren shears 
may serve as a possible guide to talc. One such shear, 
which is barren on the east side of the main ridge, may 
be followed to the Evening Star ore bodv on the west side 
of the hill. 

The occurrence of talc along contacts between mas- 
sive dolomite and stratified dolomite and limestone re- 
quires special mention. The talc frequently grades into 
country rock on the side towards the stratified material. 
As a rule there is an intermediate zone of "semi-talc," 
which may be scratched with the fingernail but which 
effervesces in acid, evidently being an intergrowth of talc 
and calcite. Within certain layers of this partly altered 
rock, true talc occurs in intermittent lenses a few inches in 
length. The talc in and near the stratified country rock 
is commonly dark brown and has stains of iron oxide, but 
the talk adjacent to the massive dolomite country rock 
is generally light-colored ore, is practically free of iron, 
and is of steatite quality. 

Principal Ore Bodies. Although there are perhaps 
a score of talc deposits at Talc City, most of the produc 
tion has come from three or four. Most of the others are 
quite small. In this report the westernmost large deposit 
(see map, pi. 1) is called the West ore body, the next one 






Talc Deposits of Steatite Grade, Inyo County 



17 



VERTICAL SECTION THROUGH SHAFT 
El. collar 996.7 ft. 




-'\ 94- FOOT LEVEL 



\ \ 

\ \ 

> 1 
\ 


£"' 


\ nvl i 


El. collar 
996.7ft 




Gently inclined raise, 
approx. 30 ft. above 
drift of upper end 



Dolomite 

PfdfH 



Stratified dolomite, 
limestone 

T40 

Contact 
(Dashed where 
approximately located) 

$50 

Fault or Shear 

showing dip 
(Dashed where 
approximately located) 

Strike and dip of beds 

■^30 

Variable dip 

a 

Shaft at surface 

K 

Shaft going above 
and below levels 

m 

Bottom of shaft 



Foot of raise 
or winze 



Head of raise 
or winze 



50 



ioo Feet 



Figukb 9. Geologic maps and section, Kast Sid., workings, Talc I ity min< 



18 



Special Report 8 



to the east is called the Central ore body, and the deposit 
at the East Side shaft is the East Side - ore body. A few 
hundred feet north of these is the Evening Star ore body. 

The West and Central ore bodies show a remarkable 
similarity in trend and geology, as indicated on the map. 
It might be supposed that they represent a single original 
deposit faulted into two segments, but this is not so. The 
country rock may have been repeated by faulting, but if 
it was, the faulting occurred before the talc was formed. 
The conjectured fault must' have been a pre-dolomitiza- 
tion structure, as no vestige of such a feature in the mas- 
sive dolomite is now exposed. 

The West and Central ore bodies have yielded the 
larger part of the Talc City output. Widespread caving 
has made it impossible to trace all the former outlines of 
the ore accurately, but Mr. W. A. Reid obligingly added 
his recollections to the writer's piecemeal restoration. In- 
tact remnants of talc still afford a good deal of first hand 
information. 

The West ore body is said to have been exploited 
first, and was once considered worked out. It was mined 
largely by means of three glory holes. On the surface the 
talc comprised an elongated zone 550 feet long, between 
massive dolomite and stratified dolomite and limestone. 
Patches of silica rock of the hanging wall terminate at a 
shallow depth (pi. 3), probably having been altered to 
massive dolomite ; the ore body also terminates at a rela- 
tively shallow depth at the localities explored to date. 
Only two downward prolongations of the ore were en- 
countered at the B level. One of these was part of a wide 
bulge, and it had various offshoots. The bulkiest portion of 
the West ore body at the B level is said to have measured 
40 by 60 feet in plan, but in many other places the width 
was only 5 or 10 feet. It is quite probable that additional 
undiscovered prongs of ore extend to depth south of the 
present B-level workings, but that region has not been 
explored. The writer believes that downward "roots" of 
the West ore body occur like the roots of a tooth. The 
south end of the ore body has moderately regular walls 
near the surface and dips steeply westward ; the irregular, 
wide north end apparently was steeply inclined toward 
the west also. Although most of the northern portion is 
worked out, part of the southern half of this ore body was 
being mined above the A level at the close of 1942. 

The Central ore body (pis. 1-3 and fig. 11) is more 
persistent at depth than the West body, but is otherwise 
similar. Although the heart of the deposit has been mined, 
this body is not worked out, and its ultimate depth is not 
known with certainty. The Central ore body extends at 
least from the surface to the workings below the D level, 
a vertical distance of almost 400 feet. According to re- 
ports, a crosscut 50 feet below the D level disclosed steatite 
ore ; here again it is very likely that downward extensions 
occur discontinuously along the strike, and some of these 
probably reach below the present workings. On the sur- 
face this talc-bearing zone is 680 feet in length, but some 
parts are so narrow they cannot be mined. The southern 
part of the Central ore body lies between massive dolo- 
mite (the footwall), and stratified dolomite and limestone 
(the hanging wall). These relations prevail from the 
ground surface to the I) level. The northern part of the 
Central ore body lacks a stratified hanging-wall formation 

--' Not to he confused with the Bast End talc mine less than a 
mile away. 



at the surface and at the B level, but the stratified dolo- 
mite and limestone are present at the C level. The mass of 
stratified rock adjacent to the ore evidently plunges north- 
ward, so it extends much farther north within the mine 
than it does on the surface. Therefore it is possible that 
the talc deposit itself will have a greater length under- 
ground than on the surface. The northern part of the ore 
body, as now exposed, consists of a shear zone incompletely 
occupied by talc that in places is only a few inches thick, 
but which swells out locally to 5 or 10 feet. This northern 
part of the Central ore body is nearly vertical at the sur- 
face, but dips to the west at depth (pi. 3) ; it was being 
re-explored on the C level in 1942. The southern half of 
the Central ore body is thick in places, a width of about 
40 feet being reported at one crosscut that is now caved. 
Large, irregular, intricate offshoots of talc occur in the 
massive dolomite footwall, and some of these can be mined. 

The East Side ore body may possibly be a branch or 
a faulted segment of the Central talc deposit. The "water- 
course" (open fault?) which is said to terminate the 
Central body, lies between the two deposits in the mine. 
However, on the surface of the ground no evidence sup- 
ports the faulting hypothesis. 

The East Side ore body is inconspicuous at the ground 
surface. Underground exposures show that it is an ill- 
defined, elongated lens with many inclusions of country 
rock (fig. 9). It dips 42°-62° SW, is 2 to 15 feet thick, 
and in late 1942 was developed for more than 180 feet 
along the strike and 100 feet down the dip. The stratified 
rocks of the hanging wall contain thin streaks of talc, 
making the west boundary of the ore rather vague. The 
footwall boundary is even less distinct, as talc containing 
dolomite inclusions grades into dolomite with interlacing 
talc stringers. 

The fourth ore body has been mined at the Evening 
Star glory holes (pis. 1 and 3) . The talc that was first pro- 
duced from this ore body was not considered entirely 
satisfactory for steatite, and about half of it was rejected 
because of limonite cubes and stains. However, after 1942 
acceptable steatite was mined from the deposit. As in the 
occurrences described above, the Evening Star ore body 
is bordered by massive dolomite on one side, and by strati- 
fied dolomite and limestone on the other side. Silica rock 
is present also. The talc-bearing zone is not as linear in 
plan as the other three ore bodies except at the west end, 
which is a steep shear containing only a foot or so of talc. 
The eastern end of the Evening Star ore body is in part a 
bulge on the same shear, but the major mass of talc is a 
stubby branch. The ore body was formerly said to extend 
downward as a funnel to a depth of only 40 feet below 
the surface, but this has been disproved by exploration 
since 1942. Mr. Henry Mulryan states that a wide con- 
tinuation of the deposit has been found at depth. At the 
surface, the ore ends toward the east against an almost 
unbroken barrier of massive dolomite, but, juding from 
the West ore body, the subsurface extent of the Evening 
Star deposit will prove to be quite different from the 
extent on the surface. 

Probable Downward Continuation of Ore Bodies. 
Because the neighboring limestone in the vicinity of the 
Talc City mine may be an ancestral rock without which 
the talc might not have developed, the former downward 
extent of the limestone is of importance. The remnants 
of limestone all dip steeply and have very little curvature, 



Talc Deposits op Steatite Grade, Inyo County 



19 







25 





TRUE NORTH ^ 



kIS 












3 » 




o 
m 
o 

r - 

o 

w a 

-< 

CD 

> r 

s o ^ 

g oto 

S Zi O 



-< 



m 



o 


o 


^- *— 




m 

CD 


m m 




o 




m 


a 






(S) 


s 


U) 






ro 




3 




> 
o 



CO 





- 





20 



Special Report 8 



indicating that the limestone once extended downward a 
great distance: the massive dolomite derived from it is 
probably likewise vertically persistent, comprising a 
great volume of rock suitable for the formation of talc. 
If the granitic rock exposed to the south extends beneath 
the Talc City mine at depth, the upper surface of the 
underlying granite may be one of the limits of the talc- 
bearing zone, but its general position at present can be 
inferred only. The massive dolomite is not noticeably 
coarser at the C level than at the H level, offering no indi- 
cation that an igneous intrusion is very close. Similar 
negative evidence is afforded by the lack of lime-silicate 
minerals in the massive dolomite. Pyrite, and limonite 
pseudomorphs after pyrite, are numerous in some of the 
deepest ore now exposed, but they are equally prominent 
in some of the talc at the surface of the ground. Finally, 
relatively few dikes are found in the mine, but dikes are 
plentiful near the granite contact half a mile south of 
Talc City. These conditions seemingly indicate that the 
upper surface of the granite has not been closely ap- 
proached by the mine workings. 

The foregoing facts do not demonstrate that talc will 
extend downward indefinitely, for temperature and pres- 
sure conditions and other factors undoubtedly played an 
essential part in the control of ore formation. However, 
it is likely that ore occurs at least a hundred feet, and 
probably several hundred feet, below the present work- 
ings. 





E X PLANATION 
Ore body ot surface 



Ore body ot B level 



Ore body ot C level 



Feet approximate 



,->.-> 











Figure 11. Generalized diagram of parts i>f the West ore body and 

Central ore body. Talc- City mine, showing variation In shape with 

depth. Composite map based on Incomplete data. 1 !» 4 2. 



•^«r 



Figure 12. Photomicrograph of silica rock from the Alliance ] 
mine showing sand ( ?) grains of quartz with later rims of chlorite. , 
Incipient mylonitization is indicated. The braided black streak 
bisecting the picture is a micro-shear zone, consisting of coherent I 
pulverized matter. This rock is the host rock for talc in the 
Alliance mine. Uncrossed nicols. 

Alliance Mine and Irish Lease 

The Alliance mine and Irish lease are on adjoining 
claims slightly more than half a mile north of the Talc 
City mine, and 6 or 7 miles northwest of the city of Dar- 
win. They are about 5,300 feet above sea level, and are i 
reached by road from Lone Pine and Keeler. Lauren A. 
Wright and the author studied these properties during 
a period of 4 days in December 1942. 

The Rocks of the Area. The areal distribution of 
the rocks is shown in figure 12. Limestone, dark gray and i 
distinctly stratified, occurs in the south part of the map 
area. Poorly preserved crinoid fragments were found in 
some places. Outcrops are gray to buff, and are numerous ! 
but not very prominent. Most of the limestone underlies 
sandstone and slate, described below, but some is also] 
found above the slate. 

Sandstone, thin-bedded and in part shaly and red-' 
dish, overlies the main mass of limestone in at least one 
place on the Irish lease. Tt is only 5 or 10 feet thick, and 
is included with the slate on the geologic map. 

Slate, mainly dark gray or greenish gray, overlies ( 
the thin sandstone member along the southern border of | 
the map area. Slate or other argillaceous material prob-j 
ably once existed in other places at the site of the Alli- 
ance mine, as some of the profoundly altered rocks in and 
near the workings are dark and rich in alumina. One 1 
such altered rock, although granulated almost beyond 
recognition, appears to have been a silty argillite ; it is [ 
exposed near the footwall of the talc deposit near the! 
Palmers' new shaft. 

Massive dolomite is the most abundant rock in the' 
northern part of the map area. For the most part it is: 
devoid of bedding and is everywhere barren of fossils. I 
It is fine to medium in grain size, compact, and tough. 
Outcrops are plentiful; they vary from pale gray to buff 
and gray black, and exhibit harsh surfaces with tiny j 
projections and depressions. The massive dolomite is a 
hydrothermal alteration or replacement of limestone.) 
Near the talc some of the dolomite lias been changed to 
soft, white, non-talcose substance. 



Talc Deposits of Steatite Grade, Inyo County 



•21 



Silica rock forms the central part of tlie mine area 
and is topographically the most prominent material, 
appearing in numerous bold outcrops which weather 
brown. Its contacts with dolomite are very sharp in many 
places. Probably the silica rock is a quartzite, as locally 
indicated by rounded to subangular "rains of moderately 
uniform size (fig. 12), but some specimens contain closely 
fitting quartz grains with mutually embayed boundaries 
(fig. 13). 

Interesting alteration products in the silica rock are 
associated with the Alliance talc deposit. Initial petro- 
graphic study points to the silica rock as the original 
material in most places. The quartz was sheared (fi»-. 12) 
and mylonitized in places, and was then hydrothermally 
altered. The resulting rock is much darker than the un- 
affected silica rock, and in fact bears scarcely any mega- 
scopic resemblance to it. The altered rock is dark gray, 
in some places tinged with dull green, and may be 
scratched with steel. In it are residual quartz grains, 
which commonly predominate over the other constituents, 
but are somewhat masked by them. Some of the quartz 
grains are "frayed", having been partly chloritized. 
Chlorite aggregates encircle these frayed grains, and fine 
chlorite mosaics are also localized in rounded areas. The 
finest constituents of the rock bave not been determined, 
and the composition of the wispy, black, mylonitic streaks 
is unknown. 

A further, or perhaps parallel, alteration of the 
silica rock has produced most of the talc at the Alliance 
mine. 




Figure 13. Photomicrograph of silica rock from the 
mine, showing incipient development of talc, which has 
the quartz grain-s.-Crossed nicols. 



Geologic Structure. The most important structural 
relations are those of the central mass of silica rock, which 
is apparently bordered by faults both on the south and 
on the northwest, as explained below. Talc occurs along 
both of these fractures. The Alliance mine is on the north- 
west fault, whereas the Irish lease is on the south fault, 

South of the silica rock, the limestone and slate dip 
northward against the main mass of silica rock (fig. 15). 
Therefore a fault exists along the discordant contact, 
unless the silica rock is an alteration product of the lime- 



. 1 m m 



Figure 14. Photomicrograph of steatite from the Alliance mine. The 

only mineral shown is talc, but tun or three other minerals occur in 

minute quantities elsewhere in the specimen. Uncrossed nicols. 

stone and slate strata which run into it. The fault, if such 
it is, was formed prior to the hydrothermal activity that 
produced talc along the border of the silica rock, and is 
now completely healed. 

The northwest edge of the silica rock is bordered by 
soft altered rocks and by talc, beyond which is massive 
dolomite. The soft altered rocks have developed along an 
east-northeast shear, and some renewed displacement has 
occurred. Slickensided surfaces are widely distributed in 
the altered rocks, but the most persistent plane of move- 
ment is that which forms the hanging wall of the principal 
talc zone; this fault surface dips gently northwest, away 
from the silica rock, and passes beneath the massive dolo- 
mite. 

Elsewhere, the bonier of the silica rock is not a fault 
contact, although many portions are relatively straight 
and decidedly discordant with respect to the strike of the 
nearest stratified rocks. No gouge, breccia, slickensides, 
or shears are present ; the silica rock and adjacent massive 
dolomite are not separated by so much as a single crack in 
many places. The outline of the silica mass is well exposed, 
and its shape shows that faulting or at least post-altera- 
tion faulting cannot account for the strange shape and 
distribution of the silica rock. 

Alliance Mine 

Ownership and History. Mrs. Edith Lockharl and 
George Koest of Darwin, California, are the owners of the 
Alliance mine, but lessees have carried on all operations. 
The Sierra Talc Company worked the deposit in 1939; 
subsequently M. C. Williams has been the lessee. Mr. 
Williams operated the mine in 1940-41, then sub-leased it 
to the T. S. Diatom Company in 1941-42, and to the Pal- 
mer Development Company in 1!I42. The latter company 
achieved the largest share of the total production, which 
is estimated to have been slightly over 4. .">(>() tons by the 
end of 1<)42. Probably at least hall' of this tonnage was 
sold for radio ceramic steatite. 

Mini Workings ami Opt ration. The surface work- 
ings are shown in plate 4. The large open pit undoubtedly 
was the site of earliest operation. In pari the pit was 
worked as a glory bole, tapped by shallow adits. 



22 



Special Report 8 



An inclined shaft near the glory hole extends to a 
depth of 70 feet, and two levels connect with it (pi. 5), 
one at 45 feet and one at 70 feet. Most of the 45-foot level 
is now inaccessible. The workings at the 70-foot level com- 
prise about 450 feet of drifts and crosscuts. Prom these 
there are several raises and large, gently dipping stopes 
that have been supported in places by square sets but 
which more generally have been allowed to cave. Rem- 
nants of an inclined winze may be discerned on the 70- 
foot level (pi. 5). This winze is said to have been sunk 40 
feet in ore. 

The talc, in 1942, was sorted at the mine into two 
grades "black" and "white," and sent by truck to 
Keeler. Here the dark variety was shipped by rail for 
milling, but the light was bought and milled at Keeler by 
the Sierra Talc Company. The light-colored talc was used 
in electrical ceramics, but the dark talc was used for other 
ceramics and for fillers. 

The Ore Zone. There is no single all-inclusive mass 
of talc at the Alliance mine, but if semi-talcose rocks are 
included there is a principal ore-bearing zone (pi. 5). 
This ore zone has formed along a system of shears ; it lies 
between the main body of silica rock and the adjacent 
expanse of massive dolomite, and it dips gently northwest 
beneath the dolomite. 

The soft hydrothermal products in the ore zone form 
a belt about 30 feet thick, and include dark-gray chloritic 
substances derived partly from silica rock and partly 
from slate or argillite, light-colored, softened, semi-talcose 
silica rock, and nearly pure talc. 

The talc has few distinct boundaries. It appears and 
disappears by gradation within the altered zone. Unlike 
the talc of the Talc City mine, it has been formed as a 
replacement of the silica rock. Well-defined masses or 
lenses of talc can rarely be found, as there is a general 
erratic blending of talc and semi-talc. However, shapeless 
masses of talc large enough to permit mining are en- 
countered commonly. The one distinct boundary of the 
talc-bearing zone is its fault contact with the massive dolo- 
mite of the hanging wall. 

Nature of the Talc. There are two varieties of ore, 
the light-colored and the dark. The light-colored talc 
varies from white to gray, and is frequently mottled ; 
the dark talc is dark gray to black. Both types are some- 
what blocky, but are cut in all directions by many in- 
cipient cracks. There is no schistose, platy, flaky, or 
fibrous texture visible to the naked eye. The grain size is 
very fine (fig. 14), most of the talc particles being 0.005 
to 0.02 millmeter long. Numerous pseudo-spherulitic 
clusters of subradiating grains are about 0.04 millimeter 
long. These are not shown in the photograph. Some of 
the clusters are elongated and some are composite, and 
in places they almost touch one another. The only min- 
erals other than talc noted by the writer were a few small 
grains of sphene, a trace of leucoxene, and extremely 
small equant specks of low relief. 

The talc is translucent on the thinnest edges only. 
Color is of no assistance in distinguishing the ore from 
associated semi-talcose rocks, and about the only simple 
criteria are "soapy feel" and softness of the talc, in com- 
parison with the adjacent materials. 

The light-colored talc, which probably constitutes 
30 percent to 50 percent of the ore in the Alliance mine, 
is steatite used for radio electric ceramics. It has been 



analyzed by the Bureau of Mines, which very kindly pro 
vided the results below : 

U.S.G.S. No. 30 — Alliance mine. From stope on 70-foot level 
Collected by Page, .5/1/42. About 100 lbs. of light-colored ore 
CaO, 0.13% ; Fe 2 O a , 0.80%. Color fired 2,300° F, light cream 
some specks. 2% impurities. 

The dark talc probably has not been used for radk 
electric purposes. It is said to be relatively high ir 
alumina, and may therefore contain pyrophyllite or chlor- 
ite. The Bureau of Mines supplied the laboratory result* 
shown below, but evidently made no test for alumina. 

U.S.G.S. No. 68 — Alliance mine. Collected by Wright anc 
Page from ore pile ; about 20 lbs. CaO, 0.16% ; Fe 2 O a , 0.74% , 
Color fired 2,300° F, light cream. Mineral impurities, verj : 
low ; abrasion, soft. 

These interesting results show that the calcium and 
iron content of the dark talc is essentially the same as 
that of the light-colored talc, and that this dark ore burns 
light. The dark talc may be steatite even though it is nol 
marketed as such. 

The Alliance ore is more chunky and less brittle thar, 
that of the other nearby mines, and would appear to be 
more suitable for lava-grade block talc. The Geologi 
cal Survey submitted block specimens to M. Kirchbergei 
& Co., Inc., for machining and firing tests. The Survey's 
samples and Kirchberger's results are shown in Table 2 

Irish Lease 

This property, immediately adjacent to the Alliance 
mine, is owned (as of 1942) by Mrs. Eva Irish, 929 Soutl 
Detroit Street, Los Angeles, California. When visited bj 
the writer it was operated by a lessee, W. J. Quacken 
bush of Darwin, California. 

Development at the claims has all been recent, appar 
ently, and on a very small scale ; the entire productior 
has amounted to only a few hundred tons. As showr 
in plate 4, there are four shafts, three of which are 
scarcely more than deep pits (8 feet, 17 feet, and IS 
feet deep, respectively). The fourth shaft, very close tc 
the others, was more than 35 feet deep in May 1942, and 
was connected with short drifts which are shown ir 
part in figure 15. 

Occurrence and Nature of the Ore. All workings lie 
along or near the contact between silica rock and slate 
(pi. 4, fig. 15), where a zone of alteration includes dis- 
continuous masses of talc. The slate dips at an angle ol 
50°-60° into the silica rock with a discordance of aboul 
20° between the two, and it is likely that a fault existed 
here prior to the formation of the talc. 

The talc, more or less enveloped in partly softened 
rock, occurs in irregular streaks, blebs, and masses thai 
are generally distributed in an elongated zone, but whicl 
individually are not all parallel with the zone. The talc 
bearing ground is at least 35 by 250 feet in plan, but onh 
a small portion is actually talc. Most or all of the tal< 
originated from the alteration of silica rock. 

The ore is fine-grained, soft, and blocky ; it is more 
opaque and more nearly pure white than the Alliance 
product. The Bureau of Mines has kindly made an analysis 
which is as follows : 

U.S.G.S. No. 67— Irish lease. Collected by B. M. Page fron 

loading chute (weight about 20 lbs.). CaO, 0.16%; FeO 

1.16% color fired 2,300° F, buff; mineral impurities, verji 

low, abrasion, soft. 



Talc Deposits op Steatite Grade, Inyo County 



Table 2 



Weigh t 
in pounds 



No. Where collected 

AIM Sierra Talc Co. mill at Keeler 3£ 

All-2 Sierra Talc Co. mill at Keeler 9i 

All-3 100-level 4| 

All-4 Carlson raise in mine 7| 



Original 
color 

Mottled gray 

Black 

Dark gray 

Dark gray 



Fit ittti 
text* 

Satisfactory 

Satisfactory 

Satisfactory 
Satisfactory 



Iron 

ii.ntli 

Low 

Low 
Low 

Medium 



Machine- 
ability 

G I 

Good 

( rOOd 

Good 



23 



Conclusion 
Best * 

Fair 
Good 

Xo value 



* This sample was the best of 22 samples tested from steatite-producing mines. 

Thus the ore appears to be well within steatite limits 
in all characteristics for which it was tested. The actual 
use of the talc, however, is unknown to the writer. 



NW 
8 



SE 



M 

ot tolc olong-^V 



drifl pmche 
plone of' sei 




E XPLANATION 



£31 

Tolc-oDserved 



Tolc-probable 



Altered silica rock 



Contoct t Dashed where 
approximately located) 



Figure 15. Cross-section 



B-B' of the 
California. 



Irish lease, Inyo County, 



White Mountain Talc Mine 23 

The White Mountain mine was studied by L. A. 
Wright and B. M. Page during 5 weeks in August and 
September 1942. 

The mine is within and adjacent to an unnamed can- 
yon on the east side of the Inyo Range, Inyo County, 
California (fig. 3). It is reached by road via Lone Pine 
and Keeler, the latter village being only 8 or 9 miles away 
by direct line, but 35 or 40 miles by road. More than half 
the road is unpaved and a part is very steep. The altitude 
of the area (between 6,000 and 7,000 feet) is such that 
surface operations are hampered by snow in the winter. 
Above the mine are spectacular limestone cliffs near the 
crest of the Inyo Range (fig. 16). The area is in the belt 
of juniper and pinon, which were formerly used for tim- 
bering the mine workings. The White Mountain mine has 
a scanty water supply, which is piped a mile or two from 
a high spring above the camp. 

13 This section has been compiled from a report by Lauren A. 
Wright and Ben M. Page. 



It is said that the White Mountain talc was known 
to Indians and that some was sold by them to the old 
and famous Cerro Gordo mine for use as a refractory. 
In 1914 Roy C. Troeger of Los Angeles, California, 
claimed the deposit, which was named the Cerro Gordo 
Xoapstone. Mr. Troeger was still the owner of the mine 
in 1942, but had never operated it. It was virtually unde- 
veloped until some time in the 1930 's when it was leased 
by the Sierra Talc Company, which came into ownership 
of the Florence and Mae West properties nearby. Mining 
of the White Mountain talc was found to be unprofitable 
to the company, so the lease was given up after about 
5 years. Ownership of the Florence and Mae West was 
retained, but no subsequent work on those two properties 
has been done directly by the company. 

William Bonham of Line Pine succeeded the Sierra 
Talc Company as operator of the White Mountain mine, 
which he has leased since 1938 from Roy Troeger. Under 
this arrangement the mine has become one of the few pro- 
ducers of steatite in the United States. 

Brief notes concerning the White Mountain mine 
have been published by Tucker and Sampson. 24 

Mine Workings and Operation. There is no inte- 
grated system of workings at the White Mountain mine ; 
instead about 40 adits, many of which were begun for 
prospecting purposes, are scattered over an area of 30 
acres. Most of the adits show at least traces of talc, but 
few have exposed minable bodies. The one place where 
interconnected workings once existed is in the central part 
of the mine, where the Sierra Talc Company drove a tun- 
nel and worked one or two additional levels. The portals 
of this tunnel are labeled 8 and 16 on the accompanying 
map, plate 6. (AH such numbers are arbitrary designa- 
tions by the writer.) 

The Sierra Talc Company mined from the glory hole 
above the aforementioned tunnel, and from a small glory 
hole near adit no. 2. Most of their production came from 
the larger glory hole. The company also drove part of 
adit no. 36 and sank a 30-foot shaft, now caved and obliter- 
ated, near adit no. 24. As they were unable to apply large- 
scale methods of mining, the company abandoned the 
operation. Nearly all of the subsequent workings have 
been made by William Bonham. 

Mr. Bonham discovered a steatite ore body just be- 
neath the ground surface and just above the old tunnel 
driven by his predecessors. The removal of this ore left 
"the Big Room" (see pi. 6). Since the exploitation of 
"the Big Room," mining and prospecting have some- 
times consisted of "gophering" by a crew of four to eight 
men. Hand drilling is preferred, most of the rock being 
soft or well fractured. When ore is found it is usually 



-'♦Tucker, W. B., and Sampson, R. J., California Div. Mines Kept. 
34, pp. 492-495,' 1938. 



24 



Special Report 8 



taken out by wheelbarrow or by mine cars and dumped 
directly into a truck, which takes it about 40 miles to 
the Sierra Talc Company's mill at Keeler. Selective blast- 
ing and shoveling are employed, but no hand sorting 
is done. 

During the time of the writer's investigation a small 
amount of ore was mined from adits numbered 11, 28, and 
2!) on plate 6. No ore was blocked out ahead of mining. 

Production. The Sierra Talc Company produced 
less than 100 tons a month from the White Mountain mine 
and probably reached a total of 2,000 to 5,000 tons. Under 
the present system, about 200 tons a month is being 
shipped and it is thought that Mr. Bonham has produced 
altogether 3,000 to 6,000 tons. This would make the out- 
put of the White Mountain mine between 4,000 and 10,000 
tons, during a period of approximately 10 years up to 
the end of 1942. 

Despite the difficulties of its operation, the mine was 
one of the two producers of steatite in the United States 
at the opening of World War II, and it still holds an 
important place in the industry. By agreement, the Sierra 
Talc Company has the exclusive privilege of buying the 
talc. 

Rock Units. The rocks at the White Mountain mine 
represent a thick sedimentary section that has been faulted 
and subjected to igneous intrusion and hydrothermal 
alteration. Certain stratigraphic relationships are there- 
fore indistinct. The sedimentary rocks contain no recog- 
nizable fossils, but a Paleozoic age is assumed from the 
presence of crinoids, corals, and brachiopods in nearby 
formations of similar lithology. Alteration near the talc- 
bearing zone has locally converted some rock varieties to 
white, pulverent materials, and in some cases the original 
rock cannot be determined. 




Figckb Hi. Part of the White Mountain mine. Camera facing- south- 
west. Photo l/.i/ L. A. Wriylit. 

1 ) Banded Limestone. A white and light gray- 
banded and stratified limestone that occurs in isolated 
masses within a massive dolomite is assumed to be the 
oldest of the rocks near the mines. It is exposed in the 
southwest corner of the White Mountain area, is separated 
from the other sedimentary units by a fault, and bears no 
relation to the talc bodies. It is the only non-inagnesian 



limestone in the vicinity and undoubtedly represents tht 
relatively unaltered portions of a rock now largely dolo 
mitized. Local distortions occur within the limestone, bui 
cannot be recognized in the surrounding dolomite. 

2) Flinty Dolomitic Limestone. A gray to black 
fine-grained flinty dolomitic limestone is the oldest rock 
east of the above-mentioned fault, within the mine area. 
The flint occurs in varying abundance as thin, discontinu- 
ous, irregular layers which are generally the main indica- 
tions of bedding. The upper portion of the limestone is in 
places characterized by well-defined bedding planes and 
by the absence of flint. This is shown in the workings of, 
the White Mountain mine north of the main canyon. 

Hydrothermal processes related to or contempora- 
neous with those producing the talc have altered parts of 
the flinty dolomitic limestone in the immediate neighbor- 
hood of the ore bodies. The two most common products of 
this wall-rock alteration are: (1) a gray, soft, micaceous 
rock superficially resembling shale, and (2) white, fibrous 
aggregates of tremolite and other silicates. Flint, where 
present, has remained unchanged in both types of altera- 
tion. 

3) Sandy Dolomite. A gray sandy dolomite that 
weathers to a buff color occurs stratigraphically higher 
than the flinty dolomitic limestone at the White Mountain 
mine. An uncomformable relationship is possibly indi- 
cated by a locally exposed angular discordance and angu- 
lar flinty dolomitic limestone blocks within the sandy 
dolomite at one place. The sand occurs as well-rounded 
grains in layers which are in places cross-bedded. These 
layers, although difficult to recognize on fresh surfaces, 
are brought into prominent relief by weathering. 

4) Silica Rock. A white to light-gray, massive silica 
rock occurs at several horizons in and above the upper 
portion of the flinty dolomitic limestone, and commonly 
separates the limestone from the overlying rocks. The 
silica rock is composed essentially of quartz, is generally 
associated with the most highly altered rocks, and is found 
near most of the talc occurrences at the White Mountain 
mine. These relations, together with its discontinuous 
distribution, would seemingly indicate a hydrothermal 
origin. The same inference may be drawn from the "jig- 
saw" texture of some specimens (fig. 17). However, a 
sedimentary origin is suggested by possible bedding 
planes, and by the rounded grains of quartz in some speci- 
mens. 

5) Massive Dolomite. A massive, coarsely crystal- 
line, white, light-buff or gray dolomite occurs at the White 
Mountain mine ; it is coarser and somewhat paler than 
that at Talc City. All such dolomite has been mapped as 
a single unit although probably several sedimentary rock 
types have been dolomitized. (Iradational contacts exist 
between the massive dolomite and both the sandy dolomite 
and banded limestone. 

A large portion of White Mountain talc occurs in a 
zone near the contact of the massive dolomite with the ; 
adjacent rocks. 

6) Dikes and Sills. Igneous rocks composing dikes 
and sills appear to be of two or more kinds. The central 
dike (pi. 6) is an intensely altered rhyolite or andesite 
with remnants of hornblende needles, vague outlines of 
feldspar phenocrysts, and specks of pyrite and limonite. 



Talc Deposits of Steatite Grade, Inyo County 



■>:. 



Pine chlorite occurs fairly abundantly in the dike. The 
rock is »Tay at depth, but near the surface the character- 
istic color is rusty and mottled. 

Some of the sills in the area are probably basic ande- 
site in composition, consisting 1 of plentiful altered feld- 
spar phenocrysts and indeterminate groundmass minerals, 
with pyroxene converted to chlorite. These sills are green- 
ish in color. 

7) Mantle. A mantle covers large portions of the 
area. In some places it is simply thick soil, in others it is 
landslide, mudflow, or ta'us material. It consists in some 
places of a single rock type, most commonly massive dolo- 
mite or silica rock, large boulders of which often appear 
to be nearly in place. In such places, however, the under- 
lying rock is not invariably the same type as that which 
predominates in the mantle. 

The mantle has an observed maximum thickness of 
15 feet where it is cut by the mine workings, but it is 
probably thicker elsewhere. Talc deposits, undiscovered 
as yet, may be complete'y covered by the mantle. 

Geologic Structure. Most of the structural fea- 
tures are shown on the map (pi. 6) and on the geologic 
cross sections (pi. 7). 

The White Mountain mine lies within a zone of north- 
west-trending faults which vary in size and continuity. 
These faults have, as associated structures, innumerable 
small, discontinuous shears with non-uniform and very 
diverse attitudes. Folding is secondary in importance and 
is partly the result of drag along the larger fault planes. 
Several of the faults are of sufficient size to be recognized 
on the surface although their traces are partly obscured 
by alluvium and mantle. The three most important of 
these have been designated as (1) the western fault, (2) 
the eastern fault, and (3) the central fault zone. 

The western fault, which is the largest and appar- 
ently the most structurally significant of the three, tra- 
verses the southwest corner of the area and can be traced 
to the northwest for more than a mile. Future mapping 
may show that it is a Bas!n and Range type of fault. It 
is characterized by a zone of dolomitic breccia and elon- 
gated dolomite blocks; this zone, within the area, averages 
80 feet in thickness and separates massive dolomite with 
its associated banded limestone on the southwest from 
similar dolomite and talcose silica rock on the northeast. 
The fault has a nearly vertical dip where it is exposed 
underground. The talc bodies are limited to the area 
northeast of the fault and similarly the banded limestone 
occurs only to the southwest of the breccia zone. Post-talc 
movement truncating the ore-bearing zone is inferred, as 
no hydrothermal effects are localized along the fault. 

The eastern fault, which also probably is of regional 
importance, crosses the northeast corner of the area. 
Mantle, however, covers a portion of its northwest exten- 
sion. Where best exposed south of the main canyon, the 
eastern fault is a brecciated zone averaging 20 feet in 
width. It is bordered on the northeast by massive dolo- 
mite and on the southwest by flinty dolomitic limestone. 
The fault dips gently westward in exposures near the 
main canyon, and steepens southeast of the canyon. A 
small andesite dike closely parallels the trace of the fault 
for a distance north of the canyon, and suggests the 
presence of an ancestral fault prior to the igneous intru- 
sion. No talc bodies have been localized along the fault. 



however, and it is probable that its more recent move- 
ment occurred after the emplacement of talc. 

The central fault zone, which is partly occupied by 
a dike, traverses the central portion of the area. It inter- 
sects two of the main talcose areas and in places contains 
talc. Recurrent movement has sheared and intimately 
fractured the dike, and has apparently caused masses to 
be separated from the main body. Underground exposures 
indicate a great local variance in the direction of strike 
and degree of dip of the dike and associated faults. Drag 
along the northeastern boundary of the dike has com- 
monly produced parallel anticlinal folding in the flinty 
dolomitic limestone and indicates a relative upward move- 
ment of the rock on the northeast side. 

One fault of the central zone is known to the miners 
as the "Black Wall" (see section B-B', pi. 7). It closely 
parallels the southwestern border of the dike in the vicin- 
ity of the glory hole. It is locally well exposed both on 
the surface and underground but cannot be extended with 
certainty for a great distance in either direction. Wher- 
ever recognized, the "Black Wall" consists of a zone of 
gouge and breccia of varying width, separating black 
flinty dolomitic limestone from light-colored silica rock. 
Talc occurs not only as crushed material within the 
faulted zone but also as discontinuous bodies within each 
wall rock. The fault changes in attitude from a northwest 
strike and a vertical dip in its southernmost exposure to 
an east strike and a gentle southward dip where last seen 
to the west. 

Whether the "Black Wall" fault existed as a struc- 
tural feature which localized the talc, or whether it de- 
veloped because a talcose contact zone offered the easiest 
relief to stresses is not certain. Obviously some movement 
has taken place since the formation of the talc. If the 
fault antedates the talc, the "Black Wall" may be ex- 
pected to extend southeastward with a reasonable degree 
of persistence beneath the mantle and at the same time 
retain its talcose nature. If the fault is younger than the 
talc, however, it would probably change its direction of 
strike to conform with the talcose border of the silica 
rock, or would distribute itself into a number of small 
barren shears. 




Figure 17. Photomicrograph of silica rock. White Mountain 

mine. The principal mineral is quartz, in interlocking urain-. show - 

ins incipient rims of talc. Crossed nlcols. 



26 



Special Report 8 



The Talc. The White Mountain talc occurs as sev- 
eral varieties, which may be grouped into three main 
categories according to color as follows: (1) light-colored 
talc, (2) moderately dark talc, and (8) "black" talc. 

(1) The light-colored talc is white to gray white to 
tan, the last tint being common near the surface of the 
ground. Most of the light-colored talc is fine-grained, and 
except where sheared it lacks foliated or platy structure 
and breaks into irregular lumps. In places the texture is 
coarse enough to impart a very fine sugary appearance. 
The light-colored talc is softer than the fingernail but 
harder than some other talcs, and is less brittle than the 
Talc City material, which it approaches chemically. An 
analysis furnished by the Sierra Talc Company is as 
follows : 



Percent 

SiO. 01.40 

A1»0 : , 1.57 

VvA), .!M) 

CaO .40 



Percent 
MgO 31.21 

Xa,<) and K 2 .19 

Loss on ignition 5.09 



100.76 



Iron Machine- Con- 
oxide ability elusion 



Good No value 



This composition, together with other favorable charac- 
teristics, places the tale among the best grades of steatite. 
This high-grade talc is derived not from the dolomite, 
but from silica rock. This is graphically indicated in 
figures 17 and 18, which illustrate the steatization of silica 
rock. Because of this origin, the main impurity found in 
the talc is quartz, rather than carbonates or tremolite 
which occur in many types of talc. 

The chunky and relatively tough nature of certain 
varieties of the ore, together with the favorable composi- 
tion, make some of it suitable for lava-grade block talc. 
The Geological Survey submitted block samples to M. 
Kirchberger & Co., Inc., for testing. The results are as 
follows : 

Where Wt. in 
No. collected lbs. Firing test 
WM-1 Mill at 

Keeler 4J Satisfactory High 

WM-2 Mill at 

Keeler — 4J Unsatisfactory Medium Good No value 
WM-3 Mill at 

Keeler 17i Satisfactory Medium Good Good 

WM-4 Mill at 

Keeler — 5 Satisfactory Medium Good Fair 
WM-5 Mill at 

Keeler 9 Satisfactory Low Good Good 

Although the foregoing data are not all favorable, the 
results are better than those obtained from most other 
California talc. No megascopic defects were noticed in 
the unsatisfactory samples prior to firing, but further 
experience might enable one better to evaluate the mate- 
rial before actual testing. 

(2) The darker talc is a neutral gray, but otherwise 
resembles the light-colored talc superficially. When 
ground it yields a white powder. This type of talc was 
formerly not accepted for radio ceramics, but in 1942 
some of it was included in shipments of steatite. A sample 
(U.S.6.S. no. 41) was sent to the Bureau of Mines for 
analysis and was found to contain only 0.07 percent CaO 
and 0.58 percent Fe 2 0a. 

('■]) The "black" talc is dark gray, but underground 
it appears to be black. When ground it yields a grayish- 
white powder. It is more brittle and more thoroughly 
fractured than the other two types, commonly occurring 







£ 















¥ 



0. 5 mm 



t 



Figure 18. Photomicrograph of silica rock partly altered to talc, 

White Mountain mine. The large grains are quartz, with frayed 

and embayed edges because of partial replacement by talc, which 

is the fine interstitial material. Crossed nicols. 

in fragments an inch or two in length. It is always asso- 
ciated with dark dolomitic limestone and is believed to 
have retained the pigment of the limestone. Very little 
importance has been attached to this talc, partly because 
it is not abundant, but some has found its way into stea- 
tite shipments. A sample (U.S.G.S. no. 40) was sent to 
the Bureau of Mines for analysis ; the CaO content was 
0.88 percent, and the Fe 2 3 was 1.06 percent, so these 
two impurities fall within the range permissible in stea- 
tite. 

There are also small quantities of decidedly green 
"talc" in and along some of the dikes and sills. It prob- 
ably consists chiefly of chlorite, but this opinion is based 
upon a cursory examination. 

All the varieties of talc merge into country rock to 
some extent ; for instance, there are all gradations be- 
tween silica rock and pure white talc. Some of the inter- 
mediate materials ("semi-talc") are difficult to distin- 
guish from pure talc. Inclusions of partly altered country 
rock are numerous in the ore bodies, and some talcose 
fragments or nodules are found to have siliceous or cal- 
careous cores. The thorough fracturing of most ore bodies 
makes it impossible to sort out all of the talc fragments 
from the intermingled impure material. 

Localization. The distribution of the talc is graph- 
ically shown on the accompanying surface map (pi. 6), 
cross sections (pi. 7), and underground maps (pi. 8). It 
is obvious that there is no single large ore body, but in- 
stead an unknown number of small ones. 

The ore controls include: (1) contacts between va- 
rious rock types, (2) faults and fractures, and (3) favor- 
able rocks, to some extent. The first might be regarded as 
a special case of the second, since some movement has 
occurred along practically all contacts in the area. In 
general, the contacts are more important than shears and 
faults within a single formation. 

Talc at the White Mountain mine is not restricted to 
any particular rock type, but the individual kinds of talc 
are thus restricted. Unimportant "green tale" (chlorite?) 
occurs in or along dikes and sills, "black" talc is found 



Talc Deposits of Steatite Grade, Inyo County 



27 



in dark dolomitic limestone, and white talc of steatite 
jrade is generally associated witli the silica rock or massive 
lolomite. For this reason a silica hanging wall is favorable. 

There appear to he certain areal restrictions in the 
listribution of the talc of this mine. Xo tale was found 
west of the western fault or north of the contact where 
the massive dolomite begins along the northern edge of 
the map area (pi. 6). In fact, only small stringers of tale 
iave been found anywhere in the massive dolomite that 
partly encircles the productive area, and this dolomite 
might be classed as unproductive except for the fact that 
a mile away it contains some of the talc bodies at the Flor- 
ence mine. 

No talc was observed in otherwise unaltered rocks. 
There is invariably other evidence of hydrothermal activ- 
ity besides the presence of talc. The hard black, unaltered 
portions of the flinty dolomitic limestone are barren, but 
(this same formation in some places has been altered to 
i paler material containing talc. The silica rock also is 
•ommonly altered, friable, and pulverent where talc is 
'ound. 

Principal Ore Zones. The geologic map (pi. 6) shows 
hat in the broadest sense there are two talc-bearing areas 
it the mine. The first is a lar»e islandlike mass that 
>ccupies the center of the terrain shown in plate 6 ; it 
•onsists essentially of flinty dolomitic limestone, and it is 
/irtually surrounded by massive dolomite. This is the 
nain producing area. The second, to the northeast, is a 
small counterpart of the first ; it consists of the same flinty 
lolomitie limestone, and is partially surrounded by the 
aassive dolomite. The following descriptions apply to the 
arjier of the two areas. 

The ore so far discovered in the main producing area 
>ccurs in two <reneral zones. The first, the peripheral zone, 
-kirts the outline of the limestone island at or near the 
•ontact with the massive dolomite. The second, the central 
pone, has not been extensively explored and may be more 
ipparent than real. Seemingly it crosses part of the island 
liagonally at or near the central fault and dike but only 
:he two ends of the central zone have been opened by mine 
workings. 

The ore bodies of the peripheral zone are flat or 
gently dipping, somewhat frajimental masses of talc and 
include country rock and semi-talc. The talc body that is 
south and west of the glory hole is over 160 feet long, 60 
feet wide in horizontal plane, and locally 12 feet thick. 
The one that is alongside and west of the "Big Room" is 
narrower, but is about 200 feet long. Both of these ore 
bodies are associated with contacts between silica rock and 
flinty dolomitic limestone or between silica rock and mas- 
sive dolomite (see pis. 6, 7 and 8). The other talc bodies 
now exposed in the peripheral zone are much smaller 
lenses and irregular masses. 

The talc of the central zone has favored the margins 
)f the central dike and the faults associated with the dike. 
One of these faults, the "Black Wall" is a westward- 
lipping fracture that in places separates black dolomitic 
limestone from white silica rock. The dark dolomitic lime- 
stone is partly altered to "black" talc, which has not 
been extensively mined. The crushed silica rock has 
locally been converted to white talc of steatite grade, rang- 
ing from a knife edge to more than 5 feet in thickness (see 
pis. 7 and 8). An example of talc localized at the mar»in 
of the centra] dike itself is to be seen in adit no. 29, where 



1 to 3 feet of moderately light-colored tab- borders the 
dike, and where "black" tab- about 1 to li feel thick bor- 
ders both the dike and the discontinuous light-colored 
talc. A much greater quantity of white talc was found 
next to the dike in adit no. 36, probably because crushed 
silica rock that was highly susceptible to alteration was 
more abundant here. 

As might he expected, the largest talc bodies so far 
discovered are at or near the juncture of the peripheral 
and the central zones. The most extensively mined area 
is near the glory hole and "Big Kooni" where the central 
dike and the "Black Wall" fault converge, owing to a 
difference in dip, and at the same time approach the mas- 
sive dolomite contact. The presence of abundant silica 
rock makes the situation completely favorable. Extensive 
mining and subsequent eaving have made it impossible 
to determine the exact size and shape of the talc masses in 
this vicinity, and evidently there are no geological records 
relating to the old workings. 

Most of the above-mentioned geological factors also 
apply to the occurrence of tale in adit no. 36. Again there 
is the central dike, the borders of which acted as loci of 
shearing and hydrothermal replacement, and plentiful 
silica rock, and the massive dolomite contact is nearby. 
Considerable tale was found here, although not as much 
as near the glory hole. 

The basal part of the mantle in the vicinity of the 
talc ore bodies locally contains abundant tale fragments 
that have remained as an insoluble residue where the 
dolomite has been removed in solution. The creep of the 
mantle has found the least frietional resistance in this 
talcose zone and has produced small shear planes in the 
mantle parallel with the surface of the ground. At several 
localities quantities of tale in the mantle were thought to 
indicate the presence of underlying ore deposits. Adits 
driven beneath showed the bedrock to be barren. It is 
probable, however, that talc bodies yet to be discovered are 
completely covered by the mantle. 

Florence Mine 25 

The Florence mine was studied by L. A. Wright and 
B. M. Page during 3 days in September 1942. This prop- 
erty is below and to the east of the White Mountain mine, 
in the Inyo Range (fijj'. 3). It is in the same canyon as the 
White Mountain mine, and is reached by the same road 
from Keeler. The Florence talc deposit is about 5,500 feet 
above sea level, and is in a pinon-covered terrain without 
a water supply. Water is hauled from the White Moun- 
tain mine. 

The Florence mine is owned by the Sierra Talc Com- 
pany of Los Angeles, and is operated for the company 
by Mr. William Bonham. 

Workings, Operation, and Production. In 1942, de- 
velopment consisted of some 40 cuts, adits, and shafts 
scattered over an area about 0.6 mile long and 0.1 mile 
wide alonjr both sides of a canyon. The accompanying 
map, plate 9, shows only the site of recent mining on the 
south side of the canyon. This was the only place where 
workings extended to any depth, and the only place where 
recent stoping had been done. The main adit here is about 
80 feet long, reaches a depth of 54 feet, and is in talc 
throughout. 

25 This section has been compiled from a report by Lauren A. 
Wright and Ben M. Page. 



28 



.Special Keport 8 




EXPLANATION 



iit* 



Talc 



Silico rock 



NfdlV'A 



Flinty, dolomitic limestone 



sd 



Sandy dolomite 



Contact, showing dip 
(Dashed where approximately located) 



Fault or shear, showing dip 
(Dashed where approximately located) 



Strike and dip of beds 
Ore chute 

B. M. Poge and L. A. Wright, 1942 



Figure 19. Map and cross-section of the main adit, South Deposit, Florence mine. 



At the time of the writer's visit to the mine, the main 
adit was not being worked. Since 1942, mining has shifted 
to the north side of the canyon beyond the area shown in 
plate 9, and talc of better quality has been produced. 20 

Some of the older workings, now partly caved and 
abandoned, must have furnished at least a few hundred 
tons of talc. The mine 's total output is not readily ascer- 
tained, but probably during its existence of about 10 
years it has produced only 1,000 to 3,000 tons. At the 
time of the geological study, production was negligible 
because the mining crew was needed at the White Moun- 
tain mine. The operation has been sporadic, but at times 
has yielded 50 tons or more of talc a week. 

Although attempts have been made to hand sort the 
ore, this is only partly successful because the material 
falls to pieces during mining and is therefore too fine to 
be sorted. 

The Sierra Talc Company, owner of the mine, mills 
the talc at Keeler and sells it for non-steatite purposes. 

General Geology. The rocks at the Florence mine 
are similar to those of the White Mountain mine, and 
may in part be identical. 

The most striking geological features are long east- 
west slivers of dark dolomitic limestone, locally flinty. 
They are embedded in an immense area of massive dolo- 
mite that is partly a coarse marble. At least a part of the 
massive dolomite originated as an alteration of the darker 
stratified rock, but in many places the two types are now 
separated by faults. 

20 Booth. Otis, oral communication. 



rather thick 
may contain 



As at the White Mountain mine, a 
mantle covers some of the terrain, which 
undiscovered talc deposits. 

The South Deposit. The southern Florence work- 
ings (pi. 9) are in the largest sliver of flinty dolomitic 
limestone. This sliver is 250 feet wide in one place, but in 
a distance of 1,000 feet along the strike it dwindles to 8 
feet in width. Its total length is well over 1,600 feet and 
may be more than a mile. This elongated sliver is locally 
or perhaps entirely separated from adjacent massive 
dolomite by southward-dipping faults. 

Some of the talc occurs in small quantities adjacent 
to a mass of silica rock and some is scattered within white, 
altered, powdery parts of the flinty dolomitic limestone. 
The bulk of the talc, however, composes a tabular body 
along a steep south-dipping fault (see fig. 19). This fault, 
where exposed in the main adit, lies well within the flinty 
dolomitic limestone sliver; but farther west it seemingly 
coincides with one edge of the sliver, which is bordered 
by massive dolomite. 

The south deposit where best exposed is from 1 to 2 
feet thick. In places it is bounded by distinct walls, but 
elsewhere there are false walls, and the true thickness has 
not everywhere been determined. The measurable length 
of the talc body is 105 feet, but talcose material occurs dis- 
continuously for 900 feet along the strike. The western- 
most showing of talc is about 450 feet beyond the map 
area of figure 6. It is not known how much, if any, of the 
talc in this deposit is steatite; much of it definitely con- 
tains too much lime. 



Talc Deposits of Steatite Grade, Inyo County 



29 



Other Talc Deposits. Several talc deposits at the 
Florence mine occur beyond the area shown in plate 9, 
and were* not mapped by the writer. 

On the north side of the canyon, directly across from 
the south deposit, a new prospect was being opened up in 
1942. A 4-foot thickness of light-gray talc was exposed 
here in a 12-foot adit. The talc is at or near the contact 
between light-colored massive dolomite and an included 
sliver of dark-gray dolomitic limestone. Talc showings 
appear discontinuously on the surface for a distance of 
180 feet to the west. 

Farther west a similar occurrence of talc is exposed 
at intervals for a distance of 75 feet. There is only one 
small excavation here. 

Still farther west, well up on the north side of the 
canyon, is an altered zone in massive dolomite. This 
altered zone is 5 to 30 feet thick, about 200 feet long, and 
contains streaks and lumps of talc that comprise 20 per- 
cent to 50 percent of the zone. An abandoned open cut 
35 by 20 feet and several other workings are in this zone. 

A more extensively mined deposit is near the western 
border of the Florence area. Caved adits, now wholly in- 
accessible, have apparently penetrated a sliver of dark 
flinty (?) dolomitic limestone, surrounded by light-col- 
ored massive dolomite which contains some silica rock. 
Near the caved portal of the workings a 6-foot thickness 
of moderately dark talc occurs between a hanging wall 
of silica rock and a footwall of dark dolomitic limestone. 
Nearby the latter rock contains an altered zone 6 to 10 
feet thick, of which about 20 percent is talc. Perhaps the 
workings that are now caved explored still other talc 
deposits. 

Below some of the deposits described above, near the 
level of the road up the canyon, is a discontinuous bleached 
zone nearly 500 feet long. Much of the zone is only 1 foot 
thick, but it ranges to 10 feet thick. In places it contains 
streaks of talc aggregating from ^ foot to 3 feet in thick- 
nesses, but in other places it is barren. This bleached 
zone is locally near the edge of a silica mass, but elsewhere 
occurs near the contact between pale massive dolomite 
and a sliver of dark flinty dolomitic limestone. It is pene- 
trated by 8 abandoned small cuts. 

In several places small veinlike streaks of talc were 
noticed in shears and joints within the massive dolomite, 
in some cases branching complexly. These small veins are 
not workable. 

The Talc. The talc at the Florence mine ranges in 
color from medium gray or tan to gray white or greenish 
white. The latter is the most prevalent tint in the talc of 
the south deposit shown in plate 9. 

The talc is universally fine-grained and lacking in 
true foliation or fibrous character. For the most part it 
has been crushed and sheared to a marked decree and 
therefore occurs chiefly in a fragmental state. The frag- 
ments of talc in the south deposit are partly separated 
from one another by thin calcite films, which may have 
been deposited by surface waters. Other megascopic impur- 
ities include scattered small calcite crystals and, less 
commonly, specks of pyrite and limonite. 

The Geological Survey submitted over 100 pounds of 
talc from the south deposit to the Bureau of Mines for 
jtesting. The sample (II.S.G.S. no. 39) showed 3.44 per- 
cent CaO and 0.86 percent Fe_>0 :! , and therefore cannot 



be considered steatite and is not sold as such. However, 
this single analysis does not condemn the whole deposit, 
which has not been systematically tested. 

Some of the talc from deposits on the north side of 
the canyon is said to be of higher quality, the CaO con- 
tent ranging from 1.26 percent to 3.0 percent. 27 The 
Sierra Talc Company has kindly provided an analysis of 
such material, which shows only 1.14 percent CaO, 1.26 
percent Fe ? 3 , and 1.72 percent A],() :i . Therefore, some 
of the talc is presumably of steatite grade. However, it is 
used in cosmetics and nonradioelectric ceramics. 

Trinity Talc Mine 

The Trinity mine is between Keeler and Darwin, 
about 1 mile southwest of the Talc City mine. In the past 
it has been known as the Pacific Coast Talc mine 28 and 
as the Angelus Talcs. Formerly owned by the Pacific Coast 
Talc Company, it has been acquired by the Sierra Talc 
Company of Los Angeles. During the last decade or two 
it was a major producer. The following data were ob- 
tained by the writer during a cursory examination May 
1, 1942, at which time the mine was idle although still 
partly equipped. 

The geological setting is similar to that of the Talc 
City mine. All the talc observed is in the massive dolo- 
mite that extends uninterrupted to Talc City, and as at the 
Talc City mine, there is at least one mass of silica rock 
within the dolomite area. Perhaps the silica rock is the 
"igneous intrusive" mentioned by Tucker and Samp- 
son. 29 The talc observed at the Trinity does not occur 
along contacts, however ; it apparently was formed by the 
alteration of massive dolomite only. The ore bodies are 
lenses that lie in several attitudes, and which were prob- 
ably localized by minor fractures. One lens must have 
been at least 40 feet long and 25 feet thick, judging by 
the size of the main excavation. The talc seems physically 
identical with that of Talc City, being pale green, fine- 
grained, and rather massive. It is believed to have about 
the same composition, and officials of the Sierra Talc 
Company affirm that it is of steatite grade. 

The workings consist of several adits, a glory hole, a 
gently inclined shaft perhaps 100 feet long, a vertical 
shaft more than 50 feet deep, and several drifts, cross- 
cuts, and stopes. 

Only small remnants of talc are now visible. Un- 
doubtedly undiscovered ore bodies exist, but their dis- 
closure is not likely without the drilling of prospect holes. 
An area that might be explored is just south of the in- 
clined shaft at the dolomite-silica rock contact. 

A more careful study of the Trinity mine should be 
undertaken to determine its potentialities. 

East End Mine and Bob Cat Claims 

The East End mine is an inactive and largely worked- 
out property less than a mile northeast of the Talc City 
mine, about 6 miles northwest of Darwin. The East End 
deposit is reached by a road from the Lone Pine-Death 
Valley highway, and was examined by Lauren A. Wright 
and the writer December 8, 1942. It was operated by the 
Sierra Talc Company some years ago, and called by them 
the East End. It has subsequently been relocated as part 
of the Bob Cat claims by R. II. Bagley. 

27 Mulrvan, Henry, oral communication. 

•"Tucker, W. B., and Sampson, R. J., California Dlv. Mines 
Rept. 34, pp. 492-495, 1938. 
28 Op. cit., p. 493. 



30 



Special Report 8 



The main deposit contains pale-green, crudely foli- 
ated, fine-grained tale. It occurs as a lens between massive 
dolomite and a pray, platy limestone from which the dolo- 
mite was derived. This lens, largely mined out, is pene- 
trated by a 60-foot inclined shaft with an adit meeting 
the shaft at the 30-foot level. Between this adit level and 
a drift at the bottom of the shaft, the talc has been stoped 
for a lateral distance of more than 100 feet, the stopes 
being 5 to 15 feet wide. Most remnants of talc around the 
margins of the stopes are very thin, from a fraction of an 
inch to 2 feet in thickness. Prom the 60-foot level an 
inclined winze 35 feet loop follows the same ore body, 
which is \ foot to 5 feet thick. At the bottom of the winze 
a 70-foot drift blocks out part of the body below the 60- 
foot level, but in this drift the tale is thin and pinches to 
1 foot at both ends of the drift. 

Within 100 feet of the main deposit, to the west and 
southwest, a cut reveals a talcose zone in a residual patch 
of stratified dolomite and limestone that is surrounded 
by massive dolomite. This talc, which is not an extension 
of the main body, is mainly very dark and hopelessly 
intercalated with country rock. Nearby, a 20-foot shaft 
exposes discontinuous talc 1 foot to 4 feet thick. 

On the other side of the main deposit, 100 to 200 feet 
to the northeast, there are two pits about 70 feet apart. 
One pit shows 6 feet of probable steatite and the other 
shows 4 feet of similar talc, but nearly continuous expo- 
sures of dolomite lie between the two pits. Thus, it is 
unlikely that a large talc body extends from one pit to the 
other. 

Still farther north of the main East End workings, 
the Bob Cat claims include a 20-foot shaft and two pits 
in separate ( ?) talc bodies 1 foot to 5 feet thick, in mas- 
sive dolomite with remnants of original stratified sedi- 
ments. 

No samples were taken, but the proximity of the Talc 
City mine together with superficial resemblance of the 
ore and identical occurrence suggest that the talc is of 
steatite grade. 

Frisco Talc Mine 

The Frisco mine was examined by Lauren A. Wright 
and the author. The geology was mapped mainly by 
Wright during two days in December 1942. The property 
is not more than a mile southwest of the Talc City mine ; 
it is 6 miles northwest of Darwin, and may be reached by 
good roads from Darwin or from Lone Pine and Keeler. 

On the Frisco no. 2 claim, a 65-foot shaft and short 
drift were made in 1942 by the Sierra Talc Company of 
Los Angeles. The shaft is between two sets of old pros- 
pects and workings made by the same company some years 
ago, but the old developments will not be fully treated in 
this report. The old operations produced "green talc" 
(chlorite, apparently) said to contain more than 20 per- 
cent alumina. After a number of years of inactivity, ex- 
ploration was resumed in 1942, and the recent shaft 
revealed talc of steatite grade. In July 1942, 100 tons of 
steatite was shipped from the Frisco. The next month only 
22 tons was produced, and altogether the small mine had 
not yielded more than 300 tons of steatite by the end of 
1942. 

The rocks are identical with those of the Talc City 
mine. Their distribution is shown in plate 10. 

Limestone, well stratified, appears in two neighbor- 
ing, strangely shaped patches. The limestone dips steeply 



westward, and the grayish strata project somewhat above 
the ground like thick shingles on n\^'. 

Massive dolomite is the most prevalent rock.. Its rela- 
tionship to the stratified limestone shows clearly that it 
has been altered from the limestone by hydrothermal solu- 
tions. The dolomite is pale gray to nearly black, free of 
fossils and stratification, and forms numerous rough- 
surfaced outcrops. 

Dikes of pale felsite (rhyolite?) are found near the 
mine. One dike is just west of the shaft, and others lie to 
the east beyond the map area. Being hydrothermallv 
altered, the felsite does not crop out well. Much of it has 
been altered to chlorite ( ?). 

Silica rock which resembles quartzite (fig. 7) occurs 
underground in the shaft and drift made in 1942. The 
steatite talc is associated with this silica rock and has been 
derived from it. 

The main masses of limestone, the felsite dike, and 
the strip of silica rock all converge toward a common 
point east of the 1942 shaft. 

As shown in pi. 10, the talc is near a felsite dike and 
close to the edge of the limestone area, but shows greatest 
affinity for the dolomite and a steeply dipping strip of 
silica rock. 

The talc body appears to be somewhat lenticular in 
shape. In the shaft it is interrupted by numerous in- 
clusions of siliceous rock, and it is probably likewise 
interrupted along the strike. The ore is pale, blocky, fine- 
grained, and soft. It is of steatite quality, as shown by its 
acceptance by the steatite industry. The talc extends down 
the shaft 50 feet, but further downward prolongation is 
rather doubtful (pi. 10). Lateral development may be 
encouraging, however, and if so, the downward explora- 
tion may be resumed later. On the surface, intermittent 
talc showings extend more than 100 feet along the strike 
and the width of the ore body is about 10 feet. 

Massive green chlorite (?) occurs abundantly as a 
replacement of parts of the felsite dikes at the Frisco 
mine. The chlorite (?), which was once produced as 
"green talc," was not being mined in 1942. About 1946 
the mining of the green material was resumed, and the 
mineral is now sold under the name "Sierralite" for use 
in cordierite ceramic bodies. It is said to have the follow- 
ing composition 30 : 

Percent Percent 

SiO. 36.24 CaO 1.47 

Fe,.0 3 1.19 Ign. loss (HaO)_ 12.19 

ALO3 23.56 CO, 0.S6 

MgO 23.39 Moisture 0.18 

Alkalis 0.35 

99.43 

Victory Talc Mine 

The small Victory mine was examined by Lauren A. 
Wright and the author in December 1942, when mine de- 
velopment was in progress. The property is 7i miles north- 
west of Darwin and 15 miles southeast of Keeler, from 
which it is reached by dirt road. The owners are Mrs. 
Edith Lockhart and George Koest of Darwin, California, 
but the lessees and operators are A. C. Palmer and Ray- 
mond Palmer of Lone Pine. Two men were working on 
the premises in December 1942. 

3,1 Analysis kindly furnished by Mr. Henry Mulryan. 



Talc Deposits of Steatite Grade, Inyo County 



31 



The talc is only 3 to 5 feet wide on the surface of the 
<rround, and barren trenches across its projected path limit 
the length on the surface of the "round to 50 feet along the 
strike. The country rock is gray massive dolomite of the 
type found at the Talc City mine a mile away. There is no 
visible structural control of the ore. 

The talc crops out on a hillside, and the ore was fol- 
lowed downward by a shaft about 25 feet deep. A 170-foot 
adit driven about 50 feet lower than the shaft collar had 
failed to intersect ore in 1942, although it seemingly 
passed under the shaft. It was later learned that a raise 
reached the talc 12 or 18 feet below the bottom of the shaft. 
The quality of the talc is probably good, judging from the 
resemblance to nearby steatite deposits. 




100-ft 
(Y\ drift 



EXPLANATION 



mm 

Talc 



Silica rocK 



dol 



Dolomite 

Contact ( Dashed where 
approximately located) 



Fault or shear 



10 5 

i 



10 



Feet 



B.M.Page 1942 



Figure 20. Cro.sx-section, Viking talc mine. 
Viking Talc M ine 

The small Viking talc mine is 16 miles southeast of 
Keeler and 10 miles northwest of Darwin, and just north 
of the highway to Death Valley. The owner is Mrs. Edith 
Lockhart of Darwin, who had leased the property to Mr. 
Wilcox in April 1942. At that time one man was employed, 
and no ore was being produced. 



There is a 20-foot shaft on the premises with two 
drifts at the bottom, one extending 20 feet and the other 
about 100 feet eastward. These workings arc partly in talc 
and partly in country rock. On the surface SO feet east of 
the shaft there are a 30-fool trench and a short adit that 
exposes 1 foot to ."> feet of tale; 15 feet farther east, a pit 
exposes 2 to 3 feet of tale in stringers. 

The rocks are similar to those at other talc mines in 
this region. Light-gray to black massive dolomite pre- 
dominates, but within it is an intermittent, apparently 
steeply dipping strip of silica rock that resembles .piartz- 
ite. The talc occurs sporadically and irregularly along this 
siliceous material (see accompanying cross section, fi<>-. 
20), and probably was derived from it. 

The talc is white, opaque, blocky, and soft. It has some 
superficial orange-red stains (which are commonplace in 
the district) and a few limonite cubes. No sample was 
taken, but nearly all the talc in the district is of steatite 
grade except where obvious impurities are too abundant. 

White Swan Talc Mine 

The White Swan nunc or prospect is perhaps a mile 
west of the Viking property and is easily reached by road 
from the Lone Pine-Keeler-Death Valley highway. It is 
15 miles southeast of Keeler and 11 miles northwest of 
Darwin. The writer was there for only a few hours in April 
1942. The owner is Mrs. Edna M. Towers, 316 West Im- 
perial Highway, Los Angeles. The former lessee was a 
Mr. Wilcox, but no one worked the mine during 1942. 

Development includes two shafts less than 30 feet 
deep, partly in talc, and two or three adits less than 50 
feet long in separate talc showings. The main working, 
however, is a branching adit shown in figure 21. One 
branch is over 400 feet long and mostly barren, while the 
other is about 50 feet and was chiefly in ore. The short 
branch was expanded into a stope which must have yielded 
400 tons of talc. Total production cannot have exceeded 
700 tons. 

The country rock and ore are superficially identical 
with those at Talc City. The country rock is massive gray 
dolomite, and the talc is fine-grained, blocky, and pale 
green. The ore occurs in frayed lenses and streaks, which 
dip steeply. The largest lens (see fig. 21) is visible for 125 
feet along the strike but is only 1 foot to 5 feet thick. It 
has been mined up and down the dip about 30 to 40 feet. 
The continuation of the workable portion may be down- 
ward and to the west. The talc has been localized by minor 
fractures rather than by contacts between rock types ; it is 
chiefly bounded by dolomite, although some silica rock 
was noted nearby. 

Lakeview Talc Mine 

The Lakeview mine is idle, having seemingly been 
worked out. It is 2\ miles north-northwest of Keeler, near 
the foot of the Inyo Range but about 4,400 feet above sea 
level. The loading bin is reached by road from Lone Pine 
or Keeler, and the mine itself is 100 yards or so above the 
road on a steep hillside. 

A. C. Palmer and Raymond Palmer of Lone Pine 
were the operators of the property during its chief activ- 
ity, and probably produced between 1,000 and 3,000 tons 
of talc. The following data were collected by L. A. Wright 
and the writer in December 1942. 



32 



Special Report 8 



Talc stope to 

i^BQ surface 

^ Broken line = 
Y ^^\ ^j^level 22 ft above 

15- ft/ 
winze 6- ft 




Dolomite 
62 
Foult or sheor, showing dip 

pen cut 

S 

Head of raise or winze 

too Feet 



Figure 21. Cross-section, White Swan tale mine. 

A vertical shaft 30 to 50 feet deep connects with one 
visible level at the bottom. From this level there are two 
principal stopes that almost reach the surface. They are 
close together, steep, and en echelon ; one is about 25 feet 
long and the other is 45 feet. Both stopes are 3 to 10 feet 
wide and 2 to 40 feet high. The floors are concealed, but 
at one end of the pair of stopes the ore pinches out and 
the other end is very near the surface of the ground, 
owing to the steepness of the hillside. 

One stope is in a steep lens of talc between quartzite 
and stratified gray dolomite or limestone. Dark talc 
occurs near the latter, and white talc near the quartzite. 
The other stope is along a steeply dipping talcose sliver 
of dolomite or limestone that is enclosed in a diabase dike. 
The diabase itself is not talcose. The ore remnants appear 
to be of high quality, and are probably steatite, but they 
were not sampled by the Survey. 

Blue Stone Talc Mine 

The Blue Stone mine is small, inactive, unequipped, 

ami perhaps largely worked out, but the remaining talc 

is probably of steatite quality. The property is on the 

side of a canyon on the west side of the Inyo Range, 10 



eel 
;he 



miles from Independence, and is reached by dirt road via 
Mazurka Canyon (see Mt. Whitney quadrangle). The 
railroad at Kearsarge is 9 miles away by road. 

Walter Sorenson of Lone Pine, California, is the 
owner, and W. H. Huntley of Bigpine was a recent lesseel 
Mr. Huntley accompanied Lauren A. Wright and th 
writer during a 3-hour examination of the mine Nove 
ber 30, 1942. 

Talc was noticed here by Goodyear 31 in the 1880 's. 

The predominant rock is thick-bedded, dark-gray 
Devonian (?) limestone containing discontinuous thin 
streaks of flint. The strata dip steeply but uniformly 
westward. Interbedded with the limestone is a quartzite 
member possibly 20 to 60 feet thick, which forms the foot- 
wall of the main ore body. The talc occurs within the 
limestone, from which it was derived. 

The main ore body is nearly mined out, its site being 
outlined by a steep lenticular stope that measures about 
40 by 40 by 10 feet along its principal axes. The stope, 
which yielded the entire 800-ton output of the mine, con- 
nects directly with the surface of the ground. From the 
lower end of the stope, a chute leads to an adit about 50 
feet below. This adit, which was driven in from the moun- 
tainside, is 100 to 200 feet long, and although it passes 
beneath the ore body and follows the controlling lime- 
stone-quartzite contact, it does not intersect any ore. The 
downward limit of the stoped body is thus quite definite, 
and the longitudinal limits are implied by the fact that 
the ore pinches to 12 or 18 inches at each end of the stope. 

Other intermittent talc showings 1 foot to 2 feet wide 
occur on the surface north of the main deposit, but are 
not visibly connected with it. About a third of a mile 
south of the main ore body, talc as much as 2 feet in 
width is exposed for 50 feet, partly in two small adits. 
This talc is bounded by flinty limestone, with no quart- 
zite, but is not far off strike from the main body. There 
are other small, discontinuous showings of talc. 

The ore at the Blue Stone is mainly mottled gray, 
soft, blocky, massive talc. The Bureau of Mines kindly 
reported as follows on a sample : 

I'.S.G.S. Xo. 6") — Blue Stone mine. Collected by Wright and 
Page, 11/.SO/4L' (about 15 lbs.). CaO. 0.10%; Fe s 3 , 0.42%; 
color fired 2300° F, white; mineral impurities, very low; 
abrasion, soft ; Tuscaloosa laboratory rating, O.K. 

The material is probably of steatite grade. 

Willow Creek Talc Mine 

This mine, although small, has reportedly yielded 
talc of steatite grade. It is now apparently worked out, 
having produced a probable total of about 1,000 tons, 
mostly within a year's time. Lauren A. Wright and the 
writer gathered the following data during May 1942, near 
the termination of mine operations. 

The deposit is on the steep south side of the valley of 
Willow Creek, which runs through the east flank of the 
Inyo Range and empties into the north end of Saline 
Valley. The Willow Creek mine is reached from Bigpine 
by a poor dirt road, the same one which leads to the White 
Eagle mine. The approximate longitude and latitude are: 
117° 56' 15" west, and 36° 50' 40" north (see Ballarat 
quadrangle). The owner is Emil Carlson of Bigpine, Cali- 
fornia. Almost all the development and mining have been 
done by a lessee, G. P. Rogers of Bigpine. 

3i Goodyear, W. A., California Div. Mines Rept. 8, p. 268, 18S8. 



Talc Deposits of Steatite Grade, Txyo County 



33 



The geology is unusual in that the mine appears to 
be in a landslide or an incipient landslide. There are large 
topographic benches farther up the mountainside, and the 
mine workings are in a highly fractured, extremely un- 
table rock mass with many gaping cracks. The most preva- 
lent rock is granite. Within it are pendants of white lime- 
stone, and along the edge of one pendant a lens of talc 
occurs, as shown in the accompanying figure 22, which 
indicates the outline of the ore prior to mining. The talc 
in us( have been at least 20 feet thick at its widest part, but 
it narrows rapidly along the strike. It lies transversely 
across a ridge and does not appear at lower levels in the 
[ravines on cither side of the ridge. 



The outlines of the talc ond 
limestone are shown as they 
were prior to mining. 



Glory hole 



\y 



ft 



r,V4tc 



^ 



yt ..\l^^.~-i^ J ..Cj-n.„ ■ ■■■: ■■v.-:,-.y \ S \ \ '\ 



vel 



NW 



EXPLANATION 



MsM 



Talc 



*m 



Granite 



ssa 



Limestone 



Contact (dashed where 
approximately located) 



i i i i i ■ i i i 



50 



ioo Feet 



LA. Wright and B.M Poge,l942 



Figure 22. Cross-section, Willow Creek talc mine. 

The deposit was mined mainly from two adits which 
tapped a glory hole. The ground was initially thoroughly 
fractured by natural movement down the steep mountain- 
side, and it was further disturbed by the mining. The 
lower adit was kept open with great difficulty and consid- 
erable danger and expense. 

The talc is gray-white, fine-grained, and bloeky, out- 
wardly resembling the associated limestone. Officials of 
the Sierra Talc Company, which purchased the ore, say 



that it is of steatite grade. 32 There is probably additional 
talc somewhere on the mountainside above, if the Willow 
Creek deposit is actually in a landslide, but unfortunately 
the slope is partly covered by other slides. 

White Eagle Talc Mine 

Geologically, the White Eagle mine is of interest be- 
cause much of the talc has been derived from the alteration 
of granite. It is doubtful, however, that the talc is of 
steatite quality. 

At the outset of World War II, the newly developed 
White Eagle mine was considered to be a potential source 
of steatite. Subsequently, either because of difficulties in 
sorting out impurities, or because of variability in the 
quality of the deposit, a controversy arose as to the utility 
of the talc. A leading radioceramics manufacturer tenta- 
tively approved the material, but later condemned a car- 
load shipment. Some large samples have given unsatis- 
factory analyses, while some small samples appear to be 
of steatite quality. If the talc of the White Eagle mine can 
be used for steatite, it represents a large reserve. 

Lauren A. Wright and the author studied the mine 
during May, 1942. The origin of the talc has recently been 
discussed by Wright. 33 

The White Eagle mine is on the very steep eastern 
slope of the Inyo Range overlooking Saline Valley, Inyo 
County, Calif., 1 mile south of Willow Creek. The work- 
ings are about 3,600 feet in elevation, the ore bin at the 
bottom of the aerial tram is approximately 2.500 feet, and 
the main camp (near the mouth of Willow Creek) is at 
an elevation of around 2,300 feet above sea level. Soil and 
vegetation are scanty along the arid eastern side of the 
Inyo Range. 

The camp is reached by a circuitous route from the 
Owens Valley highway. Automobiles must enter Saline 
Valley at the north end, following the Bigpine-Waucoba 
Canyon road. The road is partly steep, rough, tortuous, 
and generally unsatisfactory. Prom the foot of the moun- 
tain the mine is accessible only by a trail about half a mile 
in length. 

History, Operation, and Production. Mr. Elmer 
Oaks of Bigpine is the discoverer of the talc deposit. The 
property was not exploited until 1941 when it was leased 
to Mr. Wright Huntley of Bigpine. The mine was bought 
by the Sierra Talc Company in 194.5, but it is still leased 
to Mr. Huntley. 

Initial development of the property included the 
driving of three short adits one of which is in talc through- 
out. At the site of the latter adit, an open cut was made. 
Talc is mined from this cut, which has been enlarged and 
benched. After being hand-sorted, the talc is taken to the 
foot of the mountain by means of a 2,000-foot jig-back 
aerial tram. 

During the first year of production (1941-42) the 
mine was inactive a good part of the time. An effort was 
being made to produce talc of steatite grade, but sorting 
of the ore was difficult and only partly successful. About 
1,570 tons of talc was produced in 1941, beginning in 
August of that year, but only 700 tons was shipped in the 
first 5 months of 1942. Altogether, 2,270 tons had been 



3 - Booth, Otis, oral communication. 
"Wright, L. A.. White Eagle talc deposit: an example of stea- 
tization of granite: (abst) Geol. Soc. America Bull., vol. a9, l>. 138a, 

1948. 



:u 



Sl'KCIAI. lkKl'OKT S 



3620 
3600 - 
3580 - 
3560 - 
3540 J 


•SW 

A 

+ ^\ 

^*— + +N—-— Crest of 
• -~N + +\ minor ridge 

'. + +9' +\y 

+ +\ 
t +\ 
+ +\ 
* +\ 

o es 


E XPLANATION 




tc 




Gro 

Bench 

Vi-i Do 

\ '•■■• \ Foce of cu 
\ Tol 

V 

*° Adit, projected" fc 


Tolc 




+ r+r + 




nite rock with 
DUS inclusions 


>: . /VV 
i dt>l 




omitic morble 
t 

JS 

Track yy~~^ 

1 + X 

/ dol^ + + \ 

i ' i '■ - gr + \ NN £ 

B M Poge 1942 


FEET 


line of section 



KlIil'KK - 



.logii 



■tiim Hi main (jujirry, VVhitK ICsigh> mini 



produced up to the time of this investigation. The talc is 
trucked 187 miles to the Sierra Talc Company mill at 
Keelcr. 

The Rocks and Geologic Structure. The east slope 
of the Inyo Range is an eroded fault scarp, steep and 
almost devoid of soil. The rocks near the base of the slope 
are sheared and crushed, but the mine itself is farther 
removed from the marginal fault which bounds the range, 
and considerable continuity was observed in the various 
rock units. The steepness of the escarpment has caused 
some landsliding, however, even at the site of the talc, 
deposit. 

The area] geology is shown on the accompanying map, 
plate 11. 

Silica rock occurs as an elongated body. It probably 
is quartzite and displays faint stratification, /unlike the 
silica rock of the Talc City mine. Possibly it has been 
altered to dolomite in places, as its thickness varies con- 
siderably where it is bordered on both sides by dolomitic 
marble. 

Dolomitic marble is one of the oldest rocks at the 
mine. It is light, warm brown on weathered surfaces, but 
where freshly broken it is white to gray. Much of the 
dolomitic marble is sufficiently coarse that the cleavage 
surfaces of the constituent crystals are readily visible at 
a casual glance. 

Granitic material (probably granite or quartz mon- 
zonite) has invaded and partly engulfed the silica rock 
and dolomitic marble. The granite is moderately dark 
gray, and contains both biotite and hornblende ; the grains 
arc small to medium in size. Numerous included slivers 
and blocks of dark schists and some basic igneous rocks are 
present within the granitic mass. 

In general the rock units occur in roughly parallel 
bands, as seen in plan, but there is much local irregularity, 
the granitic rock is moderately discordant in its relations 
with the other rocks. The dolomitic marble appears in iso- 
lated patches as well as in continuous bands. The silica 
rock varies in width and terminates abruptly at both ends. 
The talc body likewise is not tabular nor lenticular in 
form. These irregularities in the areal pattern of the rocks 



are Ihe result of igneous intrusion and hydrothermal al 
tcral ion rather than folding, fault ing, or other mechanics 
deformation. 

Despite the lack of uniformity in detail, all of tin 
mappable units strike nearly north-south, and in genera 
diji westward. 

Only one fault, a minor one, is shown on the map 
However, the footwall of the northern portion of the tak 
is a distinct plane which is either a joint or a shear plane 
On the whole, joints are notably abundant in this area. 

The Talc. Landslide and talus material locally cover 
the talc, and prior to the excavation of the open cut, it 
appeared that there were two main deposits rather than! 
a single large body. 

In plan the talc body is "I/' shaped, consisting of 
two contiguous segments of unequal thickness that are at 
right angles (see pi. 11), and which dip more or less 
Inward one another. The lengths of the segments are re- 
spectively about 250 and 200 feel. The corresponding map 
widths are 88 and !'"> feet, but these figures do not repre- 
sent the true thicknesses. Taking into account the dip of 
the talc, the slope of the ground surface, and the irregu- 
larity of the granite contact, the thickness of one branch 
of the talc body is locally 138 feet (fig. 23) and that of 
the other branch is locally 4(J feet. 

The talc grades into dolomitic marble, granite, and 
silica rock, and was almost certainly formed by hydro- 
thermal alteration of all three. It contains partly replaced 
inclusions of the three rock types. These inclusions are 
numerous and are one of the most troublesome features 
of the deposit. They range from less than 1 inch to more 
than 5 feet in diameter, and commonly resemble rounded 
nodules of talc. The talc composing the exterior of the 
nodules grades into a core of granitic rock, dolomite, or 
silica rock as the case may be, granitic cores probably pre- 
dominating. Skill is required in sorting out these inclu- 
sions, which are usually not broken open during mining 
and which therefore exhibit only the talcose exterior. 
Their volume is of some importance but has not been 
accurately ascertained. Inspection of the quarry face sug- 
gests that they constitute between 5 percent and 20 percent 




Figure 24. Photomicrograph of partly talcose granite rock, 
White Eagle mine. The rock shown is aboul half feldspar and 
half tale. Crossed nicols. 



Talc Deposits of Steatite Grade, Inyo County 35 

»f the deposit, but the impurities may be even more abun- exposures of country nick definitely limit the ore bodv in 

hint in the southern part of the talc body. Thin sections thai direction. The thickness of the deposit, including 

>!' partly altered rock show the transition from granitic some "semi-talc", is about 15 feet. The vertical dimension 

rock to talc (fig. 24). is still unknown. 

The talc is gray white to greenish white and is fine- The country rock is mainly gray dolomite and dolo- 

prrained and structureless for the most part. It is soft but mitic marble, stratified in places. Within this material 

brittle and is so thoroughly fractured that it breaks into there is a band of silica rock that is either quartzit ■ a 

rather small pieces, increasing the difficulty of sorting it hydrothermal product. The talc occurs along the under 

by hand. In a few places the talc unmistakably exhibits a side of the siliceous rock, as shown in the accompanying 

relict igneous texture inherited from the original granitic sketch, figure 25. The ore is white next to the light silica 

rock. rock and dark next to the blue-gray dolomite, l'ossiblv 

An analysis kindly provided by the Sierra Talc Com- microscopic graphite was retained during hydrothermal 

pany fulfills commonly accepted steatite specifications, as alteration of the dolomite. It is said that the dark color 

follows: vanishes during firing. 34 

Pe _r™ nt Percent The ore is massive, blocky, soft, semi-opaque, fine- 

Si ° a r,!, - 7(! S0:| ° 03 grained, and scarcely stained even at the surface of the 

Al*Oa 8.30 Na-O 0.I8 ground. The Bureau of Mines kindly gave the following 

Fe^Os 1.10 KaO 0.14 information based upon our two samples : 

CaO 0.30 Loss on ignition. 2.38 T.S.C.S. Xo. 63— Eleanor claim. White talc, collected from 

MgO 27.81 ndit by Wright and Page, 11/29/42 (about 10 lbs. 1 ; CaO, 

T ,. .-, , , , . „ . 0.08%; VeAh, 0.95%; color fired 2,300° F, buff ; mineral 

Individual samples such as the foregoing do not rep- impurities, very low; abrasion, soft. 

•resent the bulk of the deposit, which is variable. Some U.S.G.S. Xo. 04 — Eleanor claim. Dark talc, collected from 

large samples show more than 2 percent FeoO.-j and an • 1,lit hv Wright and Page, 11/29/42 (about 10 lbs.); CaO, 

appreciable content of feldspar. ££* ; Fes ° 3 ' 073% ; color Hml 2 ' 300 ° F ' cream; abrasion ' 

: " Mulryan, Henry, oral communication. 




EXPLANATION 
tc 



White talc 



Mottled gray and 
blue-block talc 



Silica rock 



Dolomite 



Contoct (Dashed where 
approximately located) 



Figure 25. Sketch section, Eleanor talc claim. 
Eleanor Talc Claim 

The recently discovered Eleanor talc claim overlooks 
Saline Valley from a point several hundred feet up on the 
eastern escarpment of the Inyo Range. It is less than a 
mile south of the White Eagle deposit and is approached 
by the same road, but the final ascent from the foot of the 
mountain is by trail. The approximate longitude and lati- 
tude are 117° 55' west and 36° 49' 30" north, juding from 
the Ballarat quadrangle map. G. P. Rogers of Bigpine and 
Frank Henderson are the owners. 

In November 1942, Lauren A. Wright and the writer 
gathered the data of this summary. At the time there were 
several small cuts and a 30-foot adit. 

The orebody is exposed along the surface for about 
150 feet (slope distance) . The adit is near the south end of 
the deposit. About 100 feet south of the adit continuous 



BIBLIOGRAPHY 
Anon. (Page, B. M., and Wright, L. A.), Talc in the Ganim mine, 

Shasta County, California: U.S. Geol. Survey Strategic Min- 
erals Investigation, Prelim. Maps, 194."',. 
Anon., Talc: Ceramic Industry, vol. 32, pp. 38-40, 193!). 
Dana, E. S., The svstem of mineralogy of James Dwight Dana, 0th 

ed., pp. 678-680, 1904. 
Diller, J. S., Mineral Resources for 1913, I'.S. Geol. Survey, pp. 

153, 155, 157-160, 1914. 
Engel, E. A. J., Talc and ground soapstone, in Industrial minerals 

and rocks: Am. Inst. Min. Met. Eng., pp. 1018-1041, 1949. 
Goodyear, W. A., California Div. Mines Rept. 8, p. 207, 1888. 
Klinefelter, T. A., Speil S., and Gottlieb S., Survey of the suitability 

of domestic talcs for high-frequency insulators: I'.S. Bur. 

Mines Rept. Inv. 3S04, 1945. 
Knopf, Adolph, A geologic reconnaissance of the Inyo Range and 

the eastern slope of the Sierra Nevada, California, with a sec- 
tion by Kirk, Edwin, The stratigraphy of the Inyo Range : 

U.S. Geol. Survey Prof. Paper 110, 1918. 
Ladoo, R. B., Talc and soapstone: U.S. Bur. Mines Bull. 213, pp. 

111-117, 1923. 
Sampson, E., Mineral Resources for 1920, Part II. I'.S. deed. Survey, 

pp. 203-204, 1923. 
Sampson, E., Mineral Resources for 1922, U.S. Geol. Survey, pp. 

81-83, 1923. 
Tucker, W. B., California Div. Mines Rept. 17, pp. 300-301, 1920-21. 
Tucker, W. B., California Div. Mines Rept. 22. pp. 523-524, 1926. 
Tucker, W. B., and Sampson, R. J., California Div. Mines Rept. 34, 

pp. 492-495, 1938. 
Waring, C. A., and Huguenin, E., California Div. Mines Rept. 15, 

pp. 126-127, 1919. 
Wright, L. A.. White Eagle talc deposit : an example of stent izal inn 

of granite: (abst.) Geol. Soc. America Bull., vol. 59, p. 1385, 

1948. 
Wright, L. A.. California talcs: Min. Eng.. vol. Is7. no. 1. pp. 

122-128, 1950; also, Trans. Am. Min. Met. Eng., vol. IK", pp. 

122-128, 1950. 



42682 4-51 2M 



printed m California state printing office 



DIVISION OF MINES 
OLAF P JENKINS. CHIEF 



STATE OF CALIFORNIA 
DEPARTMENT OF NATURAL RESOURCES 



UNITED STATES DEPARTMENT OF THE INTERIOR 
GEOLOGICAL SURVEY 



SPECIAL REPORT 6 

PLATE I 



EXPLANATION 



sdl 

Stratified dolomite ond 
limestone; ton to block 




NOTE As nearly as possible, talc bodies ore shown 
os they were prior to mining. Most 
out at the surface before map was mode 



Geology by B. M Page, Morch 1942 
Topography by B M Page and M Erickson 



SURFACE GEOLOGY OF THE TALC CITY MINE, INYO COUNTY, CALIFORNIA 



IO0 50 



Contour interval 20 feet 

Elevations referred to cottar of main shaft, 
which is IOOO. OO feet (assumed) 



+ 



EXPLANATION 




GEOLOGY OF THE C LEVEL, TALC CITY MINE 




GEOLOGY OF INTERMEDIATE LEVELS, TALC CITY MINE 




GEOLOGY OF THE B LEVEL, TALC CITY MINE 




ology by 8 M Peg* 



GEOLOGY OF A PART OF THE D LEVEL, TALC CITY MINE 



GEOLOGY OF B, C, D AND INTERMEDIATE LEVELS, TALC CITY MINE 



STATE OF CALIFORNIA 
DEPARTMENT OF NATURAL RESOURCES 



UNITED STATES DEPARTMENT Of THE INTERIOR 
GEOLOGICAL SURVEY 



SPECIAL REPORT 6 
PLATE 3 




/.' ;.,' rZ' Limonit; cub.s I 



VERTICAL SECTION ALONG LINE B-B', TALC CITY MINE 



CENTRAL ORE BODY crest of moln rldje 




VERTICAL SECTION ALONG LINE C-C', TALC CITY MINE 




VERTICAL SECTION ALONG LINE D-D',TALC CITY MINE 



EXPLANATION 



WEST 
OREBODY 







Slrollflad dol 



VERTICAL SECTION ALONG LINE A-A', TALC CITY MINE 



VERTICAL SECTIONS, TALC CITY MINE 







EXPLANATION 



Altered dolomite 



Altered slate and silica rock 



Massive dolomite 



Contact, showing dip 
(Dashed where approximately located} 



Fault or shear, showing dip 
(Dashed where approximately located) 

S<~€0 

Strike and dip of beds 

X,o 
Strike of vertical beds 



E B 
Vertical shaft 



-A3 

Pit or open cut 
Dump 



Underground workings 
(Not all shown) 



-f 






SURFACE GEOLOGY OF THE ALLIANCE TALC MINE AND IRISH LEASE, INYO COUNTY, CALIFORNIA 



< iS 

ir 



a a 



a a 



U \$ '<Ij sj n 1! 



So 



+ 



°5 




en 




o 




z: 




^ 




(T 




O 




<: < 




Z 


Q 


or 


Z 


o 


3 


u. 


O 


i 


ir 


< 


o 


o 


cc 




UJ 


V 


o 


H 


z 


■z. 


3 


~) 




o 


U. 


o 


o 






o 


2 
O 


>- 


h- 


- 


o 


Ul 


UJ 


2 


(J) 


^ 


Q 


o 


^ 


1 


< 


< 




h- 


O) 




2 


Ul 


< 


o 


_l 


z 


Q. 


< 




_J 


O 


_1 


O 


< 


O 




_l 




o 




UJ 




CD 






BY 8 M PAGE ANO L A WRIGHT SEPTEMBER 1942 



SURFACE GEOLOGY OF THE WHITE MOUNTAIN TALC MINE, INYO COUNTY, CALIFORNIA 



1 DIVISION OF MINES 

OLAF P JENKINS. CHIEF 



SW 
A 




STATE OF CALIFORNIA 
DEPARTMENT OF NATURAL RESOURCES 



WEST FAULT 



UNITED STATES DEPARTMENT OF THE INTERIOR 
GEOLOGICAL SURVEY 



-I- 



T7V3F 

a 

A13 



+ 



EAST FAULT 



vim 



CENTRAL FAULT 
AND DIKE 





SECTION A— A' SOUTHWEST HALF 



ROAD TO KEELER 



SECTION A — A' NORTHEAST HALF 



NE 
A' 




SPECIAL REPORT 8 
PLATE 7 



EXPLANATION 



Mantle — thick soil , talu 



ez 



Talc, semi- talc and 
intermingled material 



•J < \l < 



Dike, sill , rhyolite or ande 



Massive dolomite 






Silica rock 



Flinty, dolomitic limestone 



Sanded limestone 



'1LL1I 



approximately located) 




No 16 Adit Level 



Enfronce to 
glory hole 




■f 



Fault or shear (Doshed 
*here approximately located) 



GEOLOGIC CROSS SECTIONS 

WHITE MOUNTAIN MINE 

INYO COUNTY, CALIFORNIA 



200 250 FEET 



SECTION B — B 



SECTION C-C 



DIVISION OF MINES 
OLAF P. JENKINS, CHIEF 



STATE OF CALIFORNIA 
DEPARTMENT OF NATURAL RESOURCES 



UNITED STATES DEPARTMENT OF THE INTERIOR 
GEOLOGICAL SURVEY 



SPECIAL REPORT 8 
PLATE 8 



ADIT NO. 29 



EXPLANATION 




ADIT NO 13 



ADIT NO.8 

a 59€3 



+ 





ADIT NO. 20 



ADIT NO. 18 





Tolc. semi-talc and 
intermingled material 



Dike, rhyolite or andesite 



Mossive dolomite 



Silica rock 
Flinty, dolomitic limestone 



Contact, showing dip 
(Dashed where indefinite) 



, 



Fault, showing dip 
(Dashed where approximately lacoled 
U, upthrown side. Q.downthrown side) 



Fault with variable dip 



Fault zone or shear zone 



Axis of anticline 



Strike and dip of beds 

Generalized strike 
of contorted beds 



^X> 



Underground workings 



Ore chute 



Head of raise or winze 

IS 
Foot of roise or winze 



ADIT NO. 36 




ADIT NO. 2 



GEOLOGY BY LA WRIGHT AND 6 M PAGE. 1942 



GEOLOGIC MAP OF ADITS, WHITE MOUNTAIN MINE 




Montie-soii,toius, etc 

I °°< I 

ESS 

Tolc 

I- Wl 



Contoct, shewing dip 
iOasnea nrfwra appro* 



Conceoled contact 



Fault or shear, showing dip 
imotely to cot BO") 



, Concealed toutl or shea 



Strike and dip of beds 



Underground workings 



,1 di. 



Flinly, dotomitlc limestone 
Sandy dolomite 



w- 




Generalized strike 
and dip of beds 




Verlicol shaft 




Trench or open cut 





By L A.Wright and B.MPoge 
1942 



GEOLOGIC MAP OF THE SOUTH DEPOSIT FLORENCE TALC MINE, INYO COUNTY, CALIFORNIA 



Contour interval 20 feet 

Initio! elevation assumed to be 

5500 feet of A A 



DIVISION OF MINES 
OLAF P. JENKINS, CHIEF 



STATE OF CALIFORNIA 
DEPARTMENT OF NATURAL RESOURCES 



UNITED STATES DEPARTMENT OF THE INTERIOR 
GEOLOGICAL SURVEY 



SPECIAL REPORT 8 
PLATE 10 




+ 



~SlOo 



EXPLANATION 



Talc and included matter 



Felsite, largely altered to chlorite 



Silica rocK 



Massive dolomite 



Wl 



Limestone- stratified 



Contact, showing dip 

(Dashed where approximately located) 



Fault or shear, showing dip 
(Dashed where approximately located) 



Strike and dip of beds 

H B 

Shaft at surface 

e m 

Bottom of shaft 

c? 

Open cut 



Underground workings 
Track and dump 



By L A. Wright and B M Page 
December 1942 



SURFACE AND UNDERGROUND GEOLOGY OF THE FRISCO TALC MINE 
INYO COUNTY, CALIFORNIA 



Contour interval 10 feet 
Datum is assumed mean sea level 



I DIVISION OF MINES 
OLAF P. JENKINS. CHIEF 



STATE OF CALIFORNIA 
DEPARTMENT OF NATURAL RESOURCES 



UNITED STATES DEPARTMENT OF THE INTERIOR 
GEOLOGICAL SURVEY 



SPECIAL REPORT 8 
PLATE II 



EX PL A N ATION 



Talus ond landslide material 



Talc and semi-talc 



Granitic rocks with 
various inclusions 




Dolomitic morble 



Contact, showing dip 
(Dashed where opproximotely located) 



(Dashed where approximately located) 
Strike ond dip of beds 



Trench 




+ 



Limit of quarry 



GEOLOGIC MAP OF 

THE WHITE EAGLE MINE 

INYO COUNTY, CALIFORNIA 

BY L. A. WRIGHT AND B.M.PAGE 
1942 



Bin chute 



+ 



300 FEET 

=3 



Contour interval 20 feet 

Initial elevation assumed to be 

3600 feet at A A